


Trianing

by Saiyurimai



Category: Undertale (Video Game)
Genre: Anal Sex, Bondage and Discipline, Breeding, Consensual Sex, Double Penetration, F/M, Foreplay, Foursome - F/M/M/M, Heavy BDSM, Knotting, Master/Pet, Mating Cycles/In Heat, Multi, Oral Sex, Pet Play, Punishment, Sexual Slavery, Threesome - F/M/M, Training
Language: English
Status: In-Progress
Published: 2017-12-26
Updated: 2017-12-26
Packaged: 2019-02-22 04:09:38
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 12
Words: 24,113
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13158990
Author URL: https://archiveofourown.org/users/Saiyurimai/pseuds/Saiyurimai
Summary: Frisk has fallen into the Underground and managed to get lost in the woods. When she finally finds shelter from the cold, she finds herself unknowingly falling into the clutches of a long forgotten, and dominating scientist who takes it upon himself to "train" his new pet.





	1. Chapter 1

Frisk wandered through the snow-covered forest, completely lost. She had no idea how she’d managed it but somehow, she’d gotten herself turned around and now she was just trying to look for a place to keep warm since it was starting to get a little darker in the Underground’s version of night time. As it was she wasn’t really all that dressed for the perpetual winter down here.

She tucked her hands under her arms and bit back the chill as she headed down a small hill. There was a tiny path that was overgrown with branches and bushes that looked like mostly creatures and the more animal looking monsters used.

Frisk shivered as the snow snuck into her shoes, making her feet cold and damp as she tried to hurry to find a place for the night. She managed to get to the bottom of the hill and spotted an opening among the stone wall of the mountain.

“Finally.” She whispered to herself as she trudged through the snow towards the possible cave opening so she could get out of the cold. She gave a sigh of relief as she stepped into the cave, surprised to see the scattering of echo flowers on either side of an old pathway. 

But that wasn’t the weird part. “What the-?” She whispered, her voice echoing in soft whispers around her from the flowers as she looked towards the door tucked into the wall at the other end of the path.

Inside the cave it was warmer but not warm enough for her to spend the night in. Maybe there was someone living here that would be willing to let her spend the night. 

Taking a cautious step towards the curious door she couldn’t help but wonder who could possibly live way out here. She couldn’t recall anybody that she hadn’t met in the Underground on previous trips through.

Steeling herself she reached up and knocked tentatively on the door, feeling a little bit scared as she did so. She waited before knocking again, this time a little louder in case the person inside didn’t hear her, jumping back when the door seemed to open on its own.

“H-hello? Anybody there? I just need a place to warm up for the night.” Frisk peeked her head into the darkness, barely able to make out a large room with a small kitchen with just a fridge, stove and sink, a couch and an oversized bed.

“Hello? Anyone home?” She asked out loud as she started to walk into the small home, the only light coming from the faint blue glow of the echo flowers which echoed her questions back to her. She cried out in shock as the door slammed behind her, the darkness closing in around her.

“Interesting.” A deep baritone voice rumbled behind her but when she turned there was no one there, her eyes still trying to adjust to the inky blackness of the room. “You’re much older than the humans that have fallen before. And a female.” The voice seemed to move around her, Frisk searching for the source in a frantic panic, her arms reaching out to find anything to grab onto for a weapon to protect herself if she needed it.

“Do not be afraid of me human. I mean no harm. You asked for a place to warm yourself. You can have it. I’ve no need for such things these days.” The voice seemed to fade in and out around her, sometimes appearing right next to her ear and sometimes seeming to be halfway across the room.

“Do not worry little human. I’ll leave you be. Stay as long as you’d like. My home is yours.” She could almost hear the smirk on the strangers face even though she couldn’t see him in the darkness.

After a few moments she felt as though she was alone again in the room. With a shaking hand she reached out and searched for a light switch. After a few moments she found one, flipping it on and revealing the very clearly masculine and very clean set of furnishings.

The furniture was dark stained wood, the cushions on the couch were a deep violet with grey pillows as accents. Everything was sleek, almost modern with sharp corners. Turning around she looked towards the large bed, made of similarly stained wood only it was carved into intricate designs and foreign symbols that she couldn’t understand.

The blankets looked soft and comfortable, the same color scheme of deep violet almost black, with charcoal grey and white sheets and matching pillows.

After looking around to be sure that there was no one there with her before she checked the door and locked it behind her before wandering towards the bed and curling up under the covers, taking off her damp shoes and socks. Before she knew it, Frisk had fallen into a deep slumber.

She woke up sometime the next morning to the smell of…pancakes? Groggily she woke up and peeked into the kitchen area where a plate of freshly made pancakes were waiting with a bowl of fruit sitting there. With a hint of panic she glanced around and saw that there wasn’t anyone else there.

There was also a set of clean clothes folded on the couch neatly, as if laid out there specifically for her. After a few moments, hunger got the better of her better judgement and ate the breakfast laid out. 

When she finished she looked around some more, searching for secret ways that whoever that person had been could have gotten in. She couldn’t find anything and if there’d been any cameras she couldn’t find them either.

She did find however a small bathroom with a shower and bathtub and a toilet and a small sink while she was looking around and some fluffy looking towels.

After thinking carefully Frisk decided that a shower couldn’t hurt so she grabbed the clean clothes and hurried into the shower. When she was done and dressed she felt so much better, refreshed even as she decided to sit on the couch and relax in the warmth of the stranger’s home. 

Throughout the day she watched television and relaxed on the couch, feeling at ease. When it was lunch time she found food already laid out for her in the fridge, more fruit and a sandwich. 

And around dinner time she left from going to the bathroom and found a freshly cooked meal, a salad and some grilled chicken. Frisk found it odd but she did appreciate it as she found herself hungry.

The clothes she wore were just her size, the fabric soft against her skin and comfortable. A pair of short shorts and a plain tee shirt as well as a pair of lacy underwear that fit her like a glove. 

When she was tired Frisk crawled into the bed and fell back asleep. This sort of routine occurred over the course of several days. Every morning she had fresh clothes, breakfast waiting for her. Her meals were on a regular schedule and she never saw the person making them.

It’d gotten to be so routine that she woke at the same time every morning, ate, showered and changed. Frisk knew that she was able to leave at any time but the fresh food, fruits and clean clothes was a more than tempting reason to stay so long as whoever it was allowed her to stay.

One morning she awoke to find a tall slender figure sitting on the couch, his long legs crossed elegantly in front of him, arms stretched out on the back of the couch. Frisk paused in the entry of the bedroom, unsure of what to do, but she could see a bowl of fruit on the coffee table in front of the stranger. “Good morning my dear.”


	2. Chapter 2

His voice sent a chill down her spine. “Come. Eat.” He gestured at the bowl of fruit in front of him but she hesitated. The monster looked like a skeleton like Sans and Papyrus but he had strange markings on his face. 

His hands also had holes in the palms she noticed as she looked him over carefully. “Come.” His voice deepened in an order and she slowly moved towards the bowl of fruit cautiously but she could see a sense of satisfaction cross over his face as she knelt at the table watching him. 

After a moment he tilted his head, his eye lights matching the violet of the cushions. “Eat.” Frisk yet again hesitated, unsure of what his motives were yet. When she didn’t move to eat the tall skeleton leaned forward, plucking a piece of fruit out of the bowl and held it in front of her mouth.

“Open.” He ordered, Frisk didn’t open her mouth. This caused the monster to narrow his eyes in a dangerous fashion as he pressed the fruit against her lips. “I said open.” His voice was low, commanding, an edge to his voice that sounded irritated.

Frisk opened her mouth and he placed the fruit into her mouth, using the tip of his finger to force her mouth to close again and she started to chew slowly. “Good girl.” He mused as he leaned back into his original position, watching her as she continued to eat the bowl of fruit slowly. 

“Now, I’ll not punish you for not listening today since it’s your first day of training but from here on out you’ll obey me when I give you an order. You will call me Master or Sir. From here on out I’ll be staying here as well. IS that clear?” He lifted a brow bone, looking down at her intensely, an aura of dominance radiating off of him.

“Speak.” Frisk almost flinched at the tone of his voice. “Yes.” She responded almost on reflex, surprising her. “Yes what?” He leaned down towards her again, elbows on his knees.

“Y-yes sir?” She replied and he grinned, grabbing another piece of fruit and putting it into her mouth, Frisk chewing slowly as she watched him. “That’s a good girl. Now, finish your meal and bathe. I’ll be prepping your lesson for today.” Frisk watched him stand, his body long and lean but also appearing to be muscular all at the same time under his black suit.

She watched him glide through to the bedroom out of sight and heard a few things moving around as she obediently finished her bowl of fruit. Putting the bowl into the sink to be washed later before walking into the bathroom, seeing the tall skeleton over at a wall doing something.

When she was done with her shower she reached to find her clothes and not finding anything but a fresh towel. She dried off and peeked out the door to see the tall skeleton standing patiently in unbuttoned white shirt and black slacks that hung low on his hips, his deep violet ecto body peeking through, exposing a lean muscled chest.

There were several strange looking items laid out on the bed neatly, almost like medical instruments in the way they were placed. He noticed her staring and beckoned her closer. “Come.” Frisk gulped nervously, wrapping the towel around her as tight as she could before walking towards the place he pointed to. “Good, now drop the towel.” 

Frisk shook her head, taking a step back away from him but he was quick to catch her arm, pulling her back. “Drop it.” He towered over her and she trembled in his grip. “If you’re a good girl you’ll get a nice little treat. If not then you’ll be punished. Now, drop it.” He let her go and she slowly dropped the towel, not wanting to know what kind of punishment he had in mind.

The towel bundled at her feet and she tried to cover herself as a flush of embarrassment colored her face and chest. The skeleton examined her with a pleased smirk on his face, reaching over to grab something out of her view. “Here you are. 

Now this is just for training, if you do well you’ll get a nicer one maybe.” His long fingers reached around and fastened the strip of leather around her throat. The collar was smooth against her skin as his long fingers pulled her hair out from under it, letting it splay against her back as he took a step back to examine her.

“I think now is a good time to do an examination. Lay back on the bed and spread your legs for me.” He gathered the items off the bed and placed them on an end table while she did as she was told, moving onto the bed and laying back, not quite spreading her legs as he knelt between her feet.

He sighed a little in annoyance and gripped both her knees, spreading them apart as she cried out in surprise. He pulled her hips towards him, one of his long fingers pressing against the outside of her pussy. The sensation sent a tingle down her spine, followed quickly with a gasp as his finger slipped inside. 

“Hmm. You’re tighter than I imagined. Let’s see if…” He trailed off, pushing a little deeper and hitting a barrier. “Ow! Stop!” She cried out in pain, pulling back from him but he held her in place.

He lifted a brow, a soft smirk on his face as he looked down at her as she trembled slightly from the pain. “This is very interesting. Don’t worry my pet. I know how to deal with this. I’ve done a great deal of research on humans and this is something easily remedied.” He rubbed his thumb over her clit, making her legs slam together involuntarily as she gasped at the strange new sensation.

The skeleton chuckled, pulling her legs back apart, leaning over her as his thumb continued to rub at her sensitive nub. “I’d heard that this part of female anatomy was sensitive. I’d never imagined it would be that sensitive.” His voice was low in his chest as he rubbed, his other finger pumping slowly inside of her, brushing up against her barrier.

Frisk let loose a moan much to her surprise, covering her mouth in embarrassment which made him chuckle as he reached up to move her hand from her face. “Such a pleasant sound. Tonight, I’ll work with you, teach you the very basics and we’ll work our way up from there.” 

He inserted a second finger inside of her making her moan again as tendrils of pleasure started to tingle down her spine. He leaned down, his face hovering mere inches away from hers, his breath running over her skin.

“Kiss me.” He whispered, closing the distance between them in a kiss, Frisk hesitating for a second before he pressed his fingers into her, making her gasp, allowing his tongue to slip inside.

She’d never kissed anyone before, never done any of this before and yet strangely she found herself wanting to submit to him as his tongue wrestled against hers. He continued rubbing against her clit, pumping his fingers slowly in and out, and she felt her hips lift instinctively against his hand. 

He pulled away from the kiss slightly, a smirk on his face as he removed his fingers from within her. Without thinking she gave a soft moan of disappointment at the sudden lack of stimulation.

He chuckled deep in his chest as he moved between her legs, his long tongue licking at her entrance slowly making her shudder with a rush of pleasure. “Nnngh! Hah!” She breathed as her back arched and her fingers gripped the bed sheets tightly. 

He pressed his teeth against her clit, tongue curling around inside of her, a strange sensation building in the pit of her stomach as he licked, his long hands reaching up and gripping her breasts, kneading them as he ate her out.

Frisk moaned under his touch, the sensation causing the feeling in her gut to become stronger until like a spring she cried out, arching her back she felt a release like none other. He licked her clean and sat up, wiping his mouth with the back of his hand as he looked down at her. “Such a good girl. Come here, on your hands and knees.”


	3. Chapter 3

He got off the bed and shrugged off his shirt, letting it fall to the floor to join the towel. She followed his instruction and crawled towards him, her body feeling hot and sensitive all over.

“Undo my pants for me pet.” He ordered, hands on his hips as he looked down at her, dark violet eye lights boring into her soul, daring her to defy him.

She reached over and unbuckled his belt, undoing his button and zipper slowly. Frisk looked up at him and he told her to take his pants off. Frisk grabbed the top of his pants and pulled them down, exposing the large deep violet cock standing at full attention right in front of her face. 

Magic pulsing and swirling within the thick shaft. “Touch it.” He ordered, with tentative fingers she touched the thick tip, feeling it twitch under her fingers, making her pull back which made him chuckle. 

“Go on pet. Touch it.” He guided her hand towards his cock, wrapping her fingers around it gently and making her rub it slowly from base to tip.

“There you go. Just like that.” He breathed as he let her hand go, letting her stroke his shaft with curiosity. It was so warm under her hand, pulsing with each stroke as he watched her from above.

She knew what it was but had never seen one in person before. It was just so big. The skeleton reached down and pulled her attention away from what she was doing and brushed his thumb against her lips. “I want you to open your mouth, and suck my cock.” 

Her eyes widened as she looked at the large shaft in front of her, not sure if it would even fit in her mouth. He eyed her, lifting a brow bone as he brushed her hair away from her face.

“It’s not going to fit. It’s too big.” She started to pull away but he gripped the back of her head to keep her in place, a frown of annoyance crossing over his face. “It’ll fit. Open. Your. Mouth.” He hissed through his teeth as he brought her mouth to the tip of his cock, pressing it against her lips.

He gripped the back of her head and forced the tip past her lips, shoving his cock as far into her mouth as possible making her gag reflex kick in. He let up only a little bit, letting her pull back just enough to not gag before he slowly thrust in her mouth.

“Use your tongue.” He demanded and she obeyed, using her tongue to lick the underside of his cock, flicking against his tip as he pulled back before he thrust in her mouth again. He groaned as his long fingers tangled into her hair, “Good girl. That’s a good girl.” He praised as he looked down to see her looking up at him with hints of tears in her eyes. 

He didn’t stop as he used his other hand to wipe away her tears. “Such a lovely sight.” He groaned, closing his eyes a moment as she swallowed the saliva even though some still leaked from the sides of her mouth. “Foreplay is essential for both of us. Don’t fret. I’ll take good care of you my pet.” He winked, a smirk on his face as he pumped into her mouth, giving her instructions on what to do.

Finally, he pulled out, a string of saliva connecting his cock to her open mouth for a second before she wiped it with the back of her hand. “Now, my pet. It’s time for us to move on to our next lesson.”

He curled his long finger through the ring on the collar, lifting her up towards his face as he leaned down, kissing her with a pleased smirk on his face. Frisk felt his other hand run down her side, long fingers splayed across the small of her back, pulling her towards his ecto body. She felt his hard cock rubbing up against her stomach as they kissed.

He pulled away for a breath of air as he lifted her up, her arms instinctively wrapping around his shoulders to keep from falling. “Are you ready pet?” He breathed against her lips as he moved further onto the bed, his hard cock twitching eagerly against her stomach.

“Will it hurt?” She whispered, suddenly feeling scared as she looked up at him, feeling him lay her under him on the bed. He chuckled, kissing down her throat and making her gasp. “Only for a moment my pet. Only a moment.” He moved back up to her lips, kissing her as he positioned himself in between her legs. 

She could feel him press up against her entrance, the tip pressing into her. She gasped as he pushed further into her, stretching her with his girth until he came against her barrier. “Please…it hurts…” She felt tears fall from her eyes but he only nuzzled her throat.

“Only for a moment. Relax. It’ll be over before you know it. If you’re good for me I’ll be sure to take good care of you afterwards.” Somehow those words managed to soothe her a little as she took a shaky breath, feeling him pull back slightly before plunging through her barrier, burying himself deep inside of her, his teeth biting down on her shoulder simultaneously, making her cry out in pain. 

“It hurts! It hurts so much!” She whimpered as he remained still inside of her, allowing her to adjust to his large member.

Frisk trembled under him her grip around his shoulders tight as the pain slowly started to subside. “That’s it my pet. There’s a good girl. Now let me make up for the pain. I’m going to start moving now.” He breathed, and she could sense that he was trying to hold back from the way he grit his teeth, his eye lights dark. 

“No. No please…I-“ she shook her head, but he ignored her, slowly beginning to move within her, making her gasp in a strange mixture of pain and pleasure. “You’re so tight. So warm.” He growled low in his chest as he began to pick up the pace, the pain still there but less so as pleasure began to rise. 

“Hah…hnng!” She moaned, eyes fluttering as she felt him move within her, filling her up as his hands wandered over her skin, touching and teasing in all the right places.

“That’s my girl.” He groaned as he pinned her hips into place, lifting his to penetrate her deeper, sending her moans to new heights as he hit against a sensitive spot within her. Her legs trembled as her back arched upwards, their breathing heavy as she lost all train of thought, reveling in this new sensation.

Frisk could feel that familiar spring beginning to coil within her again, her fingers digging into the ecto flesh of the skeleton, grazing against the bones underneath which elicited a growl from him as he pounded into her harder. 

“Cry for me pet. Moan for your master.” He growled as she tightened around him, her legs tightening around his waist, toes curling. “ah! Nyahhh! M-master! I-I-“ She cried out, feeling the spring release from within sending her over the edge. 

He groaned as she came, pumping harder into her until she felt him stiffen, warmth filling her up inside as he spilled his seed deep within.

He gave a few short thrusts more before he kissed her softly, breathing just as heavily as her as they came down from their climaxes. “How do you feel?” He asked as he rolled off of her, sitting up against the headboard and looking over at her as she tried to get her head on straight.

She was still sore as she tried to move, wincing slightly. “You did so well. Stay here a moment.” He winked as he got up and went into the bathroom. She could hear the water running as she managed to sit up, gasping at the blood stains on the sheets and in between her thighs.

“Don’t worry about that pet. That’s normal for human virgins and even some monsters. It only happens once and the next time won’t be so painful.” He leaned against the door frame with his arms crossed over his chest, watching her as the water continued to run in the bathroom.

“But…it’ll stain.” She stated softly as she looked back at the blood. He chuckled as he came to walk over to her, reaching his arms under her and lifting her up bridal style off the bed. “I’ll take care of that but for now, I want you to sit and relax. You did well in your first lesson.”

He carried her into the bathroom where the tub was filled with nice warm water and some sweet-smelling bubbles. He eased her into the tub, Frisk hissing in pain as the warm water hit her sensitive areas. “Easy now. I’ll be back in a moment. Let the water ease the pain.” He smiled, leaving her in the tub and going back into the bedroom out of sight where she could hear fabric being rustled and the sound of a machine humming.

After a moment he came back in carrying a small bowl of fruit, setting it on the edge of the sink. “Move forward pet.” He smiled, Frisk scooting forward, watching as he pulled his long body in behind her, both legs on either side of her as he pulled her against his chest.

“Hungry?” He asked as he grabbed the bowl of fruit, offering it to her as she took a piece. “Thank you.” She whispered as she ate, grabbing another piece as hunger started kicking in.

“You’re welcome. How are you feeling now?” He asked, placing his head on her shoulder as his arms wrapped around her middle. “I’m a little sore but I think the water is helping.” She was rewarded with a slow kiss to her shoulder as his hands sunk between her thighs, gently rubbing against her on the outside. 

“You’ll feel better soon enough.” He palmed her sore entrance slowly, massaging it under the warm water making her feel good even through the soreness. She gave a soft moan and leaned into him, one of his hands moving back up to massage her breast slowly.

Frisk raised her hips to greet his palm for better friction, the warm water surrounding them as he nipped at her skin. “Guess you’re feeling better.” He chuckled against her throat as he pushed his fingers inside of her sore entrance, making her gasp.

When the water had started to grow cold she’d already came again and was practically asleep laying against his chest as he rubbed her skin gently, whispering to her in a language she didn’t understand but felt soothed by nonetheless.

“Time for bed my pet. You’ve got a lot of training ahead of you still.” He lifted her out of the tub and helped her dry off with a fresh towel, carrying her into the bed and covering her in fresh sheets before he climbed in next to her.


	4. Chapter 4

Over the course of several months Frisk found herself submitting to her new master in all ways. Every morning they would eat breakfast together, sometimes clothed but most times she wound up not wearing anything as right after breakfast there was her training, taking a break only for lunch and to rest as she became more confident with herself around him. 

He was patient most of the time and there were very few times she’d had to be punished for disobeying his instructions. One morning she awoke ahead of her master, smiling to herself as she watched his peaceful face. Her hand moved to her throat where her new collar rested against her throat, her name engraved on a silver tag, a sense of pride filling her up as she remembered the morning her master had presented it to her.

She’d completed her training. She was now his and his alone, completely subservient to him and bending to his will automatically.

Now she was going to get up and make her master breakfast as she’d been wanting to do for quite some time. Slipping out of bed she made her way into the kitchen and started making something for them to eat.

She was just about finished when she heard her master moving around in the bedroom and she hurried to get everything plated up for him. “What are you up to Frisk?” His sleepy voice asked as he walked into the kitchen with a yawn. 

“Good morning Master. I made breakfast!” She smiled happily as she showed him what she’d made. He chuckled and came to her side, placing a hand on her head as he looked at the food. “You did. It smells delicious. It also smells like you made coffee for me.” She nodded, leaning into his touch happy for the praise.

“Just the way you like it.” She beamed as she grabbed the plates and headed into the living room, setting the plates on the coffee table as he took a seat on the couch before she came back with his cup of coffee and her juice, her tag tinkling against the metal ring with every movement. 

“Such a good girl. Thank you Frisk.” He motioned for her to come and sit on his lap and she did, leaning into the deep kiss he gave her in thanks. “Maybe I should take you out for a walk today. Would you like that?” He asked as he nuzzled her neck, still a little sleepy as he kissed her throat. 

“That would be fun. I haven’t been outside in a while I think.” She mused as he let her go, patting her on the bottom as she went to eat her meal across from him on the floor.

He smirked at her over his coffee cup at her as he took a sip and she started eating, watching him with a happy smile. They ate together mostly in silence as he turned on the television for back ground noise. 

When they were finished she gathered up the plates and washed them while he finished off another cup of coffee on the couch, completely at ease and relaxed. He invited her to lay across his lap on her stomach, his hand running up and down her spine idly as they watched television together.

She felt so comfortable that she started to doze off when he moved to run his fingers through her hair, gently tugging the tangles out of her hair.

After a few more minutes of relaxing she felt him pat her ass as a signal for her to get up off of him which she did with a long stretch and a yawn which made her master grin at her. “Come. Let’s get dressed so we can go for a little walk.” 

He smiled, winking at her as he got up off the couch, Frisk following along behind him obediently as he pulled out something for her to wear. She put on the long sleeved sweater that went down to cover the middle of her thighs and a pair of thicker leggings that would help keep her warm before going to the mirror and brushing her hair. 

Behind her she could see her master putting on an off white turtle neck and a long black cloak with black pants. She never would have guessed that she would be at this point when she fell down into the Underground. Frisk smiled happily to herself as she finished getting ready. 

He grabbed a long leather leash from atop the dresser, walking over to her and attaching it to the hook in the back. “Are you ready my pet?” She nodded and followed him obediently outside, almost forgetting all about the echo flowers that lined the path from when she first came through.

Her master wrapped her up in a warm coat before closing the door behind them and leading her towards the entrance of the cave, Frisk blinking to adjust to the brightness of the snow outside. 

“Let’s go.” Her master smiled as they walked side by side towards the snow covered forest for a peaceful walk. The crisp, cold air filled her lungs as she felt a rush of energy go through her at being outside again. “You look like you want to run. You’re not going to leave me are you?” He asked and she looked up at him with wide eyes shaking her head. 

“No! I would never leave you master. I just didn’t realize how pent up I was feeling until we got outside is all. I’ve just got a bunch of energy all built up out of nowhere.” She blushed as he chuckled, leaning down and kissing the top of her head.

“Well I wouldn’t be a good owner if I didn’t allow you to get your exercise. Go. Go ahead and run off some of that pent up energy just don’t go too far.” He unhooked her lead and pat her on the ass encouragingly as she looked up at him a little unsure.

“Go on. I’ll be right behind you.” He smiled, leaning down and kissing her deeply before nudging her ahead of him. She hesitated a moment before her pent up energy got the better of her and she took off through the snow, a happy grin on her face as she ran through the trees, looking back to see her Master walking behind her with his long legs easily making their way through the snow his hands in his pockets as he watched her carefully. 

She leapt and bounded through the snow and through the trees, realizing that she had missed being outside after all those months indoors. She was turning back to see where her Master was when she tripped and landed into something soft and warm.

“Whoa! What the-?” A deep voice rumbled as strong arms wrapped around her, both of them landing in a drift of snow. Frisk looked at the strange new skeleton underneath of her, his blue eye lights staring up at her with confusion. 

She frowned as she looked down at him, confused at seeing another skeleton around here. “Frisk!” She heard her master call out and she moved to get up, looking towards the direction of her master’s voice. “Wait wait a sec there kid.” 

The skeleton grabbed her and she glared up at him, trying to pull away from his strong grip and failing. “Who are you out here with? How long have you been out here for?” He asked and she pulled at his hand but he wasn’t letting go. She let a whimper out as she pulled away from him. 

“Let me go! Master!” She cried out, but the shorter skeleton didn’t let go even as she cried out again loudly. “Chill out kid! I’m just here to help you out! What the hell is wrong with you?” She felt tears prick at her eyes as she tried to get free from him.

“Master!” She called again, her master running through the snow, emerging from the trees with a panicked look on his face until he saw what was going on.

“Frisk, calm.” He ordered and she stopped fighting, the smaller skeleton looking at her in confusion before turning to her master who was staring at them through narrowed gaze. 

“Gaster? What the hell are you doing here? You’re supposed to be dead.” Frisk glanced between them, wanting nothing more to run to her master but the other skeleton wasn’t letting her go.

“Hello Sans. Pleasure to see you too. Now do you mind letting my pet go?” She gave a soft whine as she clenched her fists. “Your pet? She’s a person Gaster not a play thing! Who knows what you’ve done to this poor girl!” Sans pulled her towards him, stepping in front of her protectively but she was not having any of it. 

Frisk yanked at her captor and managed to slip, falling into the snow, still attached to him much to her annoyance. “Let me go! Master…” She keened as she looked over at her master. “I know pet. I know. Just be a good girl for now.” He used a calming tone, Frisk glaring up at her captor with a great deal of annoyance.

“Sans. Let her go. She wants to come to me. I’m not holding her against her will and she isn’t mistreated. If you want I can show you and then you can leave us alone in peace.” Gaster took a step forward, Sans glaring at him all the while keeping hold of her wrist. 

“Yeah right.” He hissed between his teeth. Frisk couldn’t take it anymore. She bit his wrist, the bones hard under her teeth but he let go in surprise, allowing her to get away. Frisk came to Gaster’s side, one of his arms wrapping around her as she attached herself to him, glaring at Sans. 

“Frisk. We don’t bite.” He chided and she looked away sheepishly, knowing she was going to get a form of punishment later for it.

“Come. I’ll show you that everything is perfectly fine and then you can go.” Gaster brushed aside her hair and attached the lead, Sans’s eyes narrowing in disapproval. 

He seemed about to say something but decided against it as Gaster led them back towards the house. She felt so much better being next to her master who held tight to her lead. Even though she knew she was going to be in trouble when she got home for disobeying him but she was happy not to be in Sans’s hands anymore.

When they got back to the cave she waited patiently for him to unlock the door and lead her inside, Sans following behind watching carefully. “Alright. Go to the bedroom and get comfortable. I’ll be in in a minute.” Gaster ordered and she did as she was told, stripping down and placing her clothes into a hamper and sitting quietly on the bed awaiting her punishment. 

“Sans you can stay here or you can watch, your choice. Frisk.” Frisk perked up when her master walked back in holding a plate of food for her to eat. “You disobeyed me and you bit someone. You also ran off when you told me you wouldn’t. So for that you know you have to be punished right?” She nodded looking at him. 

“Yes master. I understand.” She sat still as he came to attach a long lead that would allow her to be able to get up and go to the bathroom but wouldn’t allow her to go into the kitchen or living room to her collar and hooked the other end to the head board. “Two days. Then we’ll see how well you do before we go outside again. Alright?” Gaster knelt in front of her, tilting her head so that he could give her a kiss.

“Yes sir. I’m sorry for disobeying. It won’t happen again.” She whispered as she was handed her plate of food. “It better not. See? She’s not mistreated whatsoever.” Gaster explained as he took off his shoes, sitting on the side of the bed and glancing up at Sans who was standing in the entry way looking between the both of them as if they were crazy.

A faint blue blush on his cheekbones as he caught himself looking at her naked body. “Not mistreated?! You’ve got her tied up like some kind of animal!” She took a bite of her food as Gaster leaned up against the headboard, arms behind his head while she sat at the foot of the bed.

“She can get to the bathroom and I can bring her meals. I don’t beat her. Speak.” Gaster nudged her and she swallowed her food, looking up at Sans. “Its true. Master takes good care of me. And I knew the rules and broke them anyways. This is my punishment. He’s the best.” She smiled over her shoulder at Gaster who winked at her in response.

“Good girl.” He praised and she blushed with happiness as she returned to her meal, finishing it quickly while Sans found himself yet again staring at her. “I see you eyeing her Sans, the flush of your magic on your cheekbones is pretty obvious. She’s well trained but sometimes she can get a little bit overzealous when she’s scared. Frisk?” 

She looked over at Gaster with a tilt of her head. “Stay.” She nodded, sitting on her knees where she was, seeing Sans watching her. Gaster moved closer towards her, reaching out and rubbing her back while looking up at Sans. “I think she owes you an apology.” Sans’s eyes shot up in surprise as he got his wits about him again. 

“What? What are you talking about? I’m not eyeing her!” He denied but even Frisk could see that he couldn’t keep his eyes off of her. “Don’t try and deny it. She’s quite attractive and I’ll admit that her skin is very soft. You can touch her. She won’t bite again will you my pet?” She shook her head as she watched Sans took an unintentional step towards her before stopping himself and shaking his head.

“Go on Sans. Frisk will be a good girl.” She watched Sans walk closer to the side of the bed, Gaster standing and heading into the living room. “I’ll be out for a couple of days. I have some research that I want to work on that’s been sorely neglected over the last couple months due to training you.” Frisk looked between Sans and Gaster who was smirking at her.

“Don’t worry my pet. Sans will keep you company while I’m gone and then when I return your punishment will be over. Make sure you feed her and bathe her properly. You listen to Sans Frisk. He’s in charge.” 

Her master leaned over and kissed her before patting Sans on his shoulder and walking out the door, locking it behind him. Frisk deflated as she watched her master leave, moving back to the top of the bed and pouting a little at having been left with Sans.


	5. Chapter 5

Frisk deflated as she watched her master leave, moving back to the top of the bed and pouting a little at having been left with Sans. “So you really don’t mind him tying you up like that?” Sans asked and she shook her head, playing with her hair idly. 

“No. I don’t mind it since he treats me really well. If I’m good he gives me a treat afterwards.” She crawled towards him on the bed, “See? I got this when I finished training.”

Frisk showed off her collar with a bit of pride. He cleared his throat and looked at her, eyes trailing along her spine as she lay on her stomach. 

“But what about you calling him Master? And what kind of training are you talking about?” He asked, coming to stand next to her and she could smell the same familiar scent of magic that she’d become accustomed to whenever her master was aroused. She’d become so trained that the mere scent made her own arousal begin to heat up even though it wasn’t her master.

“He’s my master. Simple as that. I do what he commands and I obey him. He trained me to do whatever he commanded. And apparently you are now in charge so I have to listen to you and do what you command.” She licked her lips as she looked up at him, his arousal showing through his shorts. 

“Anything? What if you don’t want to do it?” He reached out and touched her back, fingertips brushing against her skin. “Then there’s a safe word. But there hasn’t been too much of a use for it. And yes I have to obey regardless or I get punished.” She bit her lip as he traced the line of her spine down to the small of her back and back up.

It was quiet between them as she allowed him to trace her spine through her skin for a moment before Sans seemed to think better of it and stepped away from her, turning towards the living room.

“I’m gonna go watch some t.v.” He said through clenched teeth as he left her on the bed, turning on the television in the living room. Frisk sighed as she calmed herself, moving back up on the bed and finding one of the books that Gaster had left for her to read whenever she wanted. 

She was about halfway through when she realized that she was hungry again. Looking over at the small clock in the room she realized it was just past dinner time and she gave an annoyed sigh. Getting up she went to the entrance of the bedroom she was able to peek her head to see Sans asleep on the couch. 

“HEY!” She yelled, making him jump in surprise, falling onto the floor which made her giggle. “Wha-?” He sat up from the floor and looked at her. “I’m hungry. You have to feed me since I’m a little tied up at the moment.” She crossed her arms over her chest as Sans got up and moved to the kitchen. 

“Was that a pun?” He asked and Frisk smirked. “Good one. What are you hungry for?” He yawned and she leaned against the wall, watching him. “Whatever you make I’ll eat. I’m just hungry. And then after dinner you have to give me a bath.” Sans flushed pale blue as he started making something on the stove. 

“Why can’t you give yourself a bath? He said the lead goes all the way into the bathroom.” He cleared his throat as she stretched, his eyes riveted to her body.

“That’s just how it’s done. But you don’t have to join in if you don’t want to. Master likes to take one with me so he can get to all the good places.” She winked, enjoying slightly how uncomfortable she seemed to be making Sans who ran his tongue over his teeth nervously. 

Her master never got flustered like this. “The good places…” He mused before clearing his throat and turned back to the meal he was making, intentionally ignoring her as she paced back and forth, eager to eat something.

“Should I uhm, unhook you or something?” He asked when dinner was finished and he looked over at her. “No. You couldn’t even if you wanted to. Master has the key.” She watched as he walked back into the bathroom and she pulled over a cushion to sit on the floor as Sans set their plates in front of them. 

“Can I join you?” He asked before sitting down and she shrugged. “You’re in charge here so you can do whatever you want.” She took a bite and was surprised at how delicious it was, it was almost as good as when Master cooked. 

“Is it good?” He asked as she took several more bites, nodding in approval. “It is. Question. What do you want me to call you since you’re in charge? Master is master but I can call you anything you like?” Frisk asked as she took a sip of her drink, looking up at him as he almost choked on his food. 

“Sans is fine. You can just call me Sans.” He blushed a little and finished his food as Frisk shrugged, already done and reaching for their plates, putting them aside and kneeling in front of him.

“So what now?” She asked, looking up at him with the tilt of her head. “What do you mean? What do you and Gaster do normally after dinner?” He asked and she hesitated for a moment before crawling into his lap, straddling him as she placed her hands on his shoulders. 

She could feel his erection through his shorts in between her legs as he stared at her. “Normally we work off the meal, then soak in the bath tub and then go back to bed. Master is quite insatiable.” She breathed, running her hands over his chest as he ran his tongue over his teeth, eye lights moving down to focus on her chest. 

“Master gave you permission to touch Sans.” Sans groaned as she ground her hips on him, rubbing her entrance over his still clothed cock. “I-I don’t want to do something to take advantage of you.” He breathed as his hands ran over her ass softly.

“Does it look like you’re taking advantage of me? Master trained me very well.” She whispered, grinding against him slowly as his eyes darkened with arousal.

Sans growled, kissing her deeply and catching her by surprise. She melted into him as he took control, his hand reaching between her legs and pulling down his shorts, exposing his cock, her already slick pussy rubbing against his thick shaft. 

“S-shit! You’re so soft and warm…This hah…mmmnngg!” He gasped as she gripped his cock, positioning him at her entrance and impaling herself on him, gasping as she took him deep inside of her all the way to the hilt.

She wasn’t given a chance to adjust before he started thrusting up into her, making her moan loudly as he grabbed her hips, lifting her up and down onto his cock. 

“Fuck you’re tight!” He groaned as he pounded into her, Frisk moaning loudly as she tossed her head back, her arms wrapped around his neck. Sans buried his face between her breasts, licking and sucking on her breasts as he thrust up into her. Her tag and lead tinkled softly with every thrust, Frisk moaning as he slammed into her g-spot.

“Sans…hah!” She breathed as he nipped at her breast, she could feel her climax coming with each thrust deep into her. “Fuck! Fuck I’m gonna cum!!” He groaned as he pounded up into her faster and harder as she tightened around him. 

Frisk cried out as she climaxed, her back arching, pressing her breasts into his face as he didn’t slow down even a bit. She felt him shoot his seed deep inside of her with a long groan of pleasure. She thought that would be it but she was wrong.

Sans flipped her around, forcing her on her hands and knees and sliding back inside of her, thrusting wildly as she cried out in pleasure, a haze over her as she succumbed to him and his hard cock.

She felt their juices mixing and running down the inside of her thighs onto the carpet as he pounded her from behind. “You feel so fucking good!” Sans hissed as he pushed her head down, stretching her body out so he could thrust into her deeper.

She moaned loudly as she felt herself reaching her second climax, toes curling in pleasure as she tightened around him, her climax was quickly followed by a third that came out of nowhere. Still Sans didn’t seem to slow down even a little as he pounded into her relentlessly, his fingers digging into her ass as he thrust into her.

Finally she felt him grow slightly within her, his breath quickening as he started to climax again. He let out a long growl as he thrust deep inside of her, filling her up to the brim before pulling out, his pale blue spunk mixing with her own and trailing down between her shaking thighs. Sans flopped back into seated position as she lay on her side trying to catch her breath, her body shaking slightly.

“I’m sorry…” Sans panted looking over at her with flushed cheek bones. She shifted and sat up against the end of the bed. “I didn’t mean to lose control like that.” He looked at her sheepishly as she shook her head. 

“You’re fine. I’ll just need to have a little help getting to the bathroom.” She smiled tenderly, nodding towards the bathroom and he nodded, getting up to go in and start the bath before coming back and picking her up off the floor, carrying her into the bathroom. 

“There’s some stuff under the sink that Master uses. He likes the smell of it on me.” Sans reached under and grabbed the bottle of sweet smelling bubbles, pouring some in as she got into the tub, relaxing into the water with a sigh. “You can join if you want to.” She peeked at him through half lidded eyes, scooting so that he had room to sit in front of her.

After a moment Sans shrugged out of his clothes and he slipped into the water with her. “Are you really ok?” He asked and she nodded, grabbing her body sponge and putting some soap on it, lathering it up and handing it to him, turning her back towards him and pulling her hair to the side. 

“I’ve been training with Master for a while now. Doing that with you is nothing new to me.” She said over her shoulder, feeling him wash her back slowly. “I shouldn’t have done that. I don’t know what came over me. Here I was trying to help you and I ended up doing the exact same thing Gaster was doing to you.” He sighed and Frisk gave a soft little giggle.

“Help me? I like it. Master is kind, he’s so smart and sweet and when he takes control…” She gave a pleased sigh as Sans moved down her back. “But you don’t know anything about him, or me for that matter.” She shrugged. 

“I know enough. He’s been nothing but good to me and you haven’t done anything to harm me so why should I worry about that? Unless you’re planning on doing something?” She turned to face him again, moving between his legs in the water.

“Are you planning on something Sans?” She asked, lifting a brow as her fingers traced up his ecto body, over his stomach and back down between his legs. Sans shivered under her touch. “Only if you keep touching me like that.” He breathed as she wrapped her fingers around his already half erect cock, stoking it slowly.

She took a deep breath and went under the water, wrapping her mouth around his cock and bobbing her head up and down while stroking at the same time. She heard Sans groan above the water until she had to come back up for air, water dripping down her face as she leaned into him, stroking his hardening shaft under the surface of the water. 

“Aren’t you tired yet?” He breathed as she kissed up his chest, over his sternum which made him groan.

“Not yet. You made me come three times so it’d be only fair to make sure you get one more.” She licked the side of his neck, a long groan as he bucked into her hand.

“Hahhh! Ah!” Sans came down Frisk’s throat as she was under the water, making her come back up for air, panting slightly to catch her breath and swallowing his seed at the same time.

“There. Now we’re even.” Sans chuckled as he leaned back against the side of the tub and staring up at the ceiling with heart shaped eye lights. “Yeah. I guess we are now huh.” 

Frisk yawned, stretching as she started to get out of the tub, all cleaned off and ready for bed now as she grabbed a towel and started to dry off, Sans waiting a moment before following suit, draining the tub and drying off. Once dry she crawled into the bed where she normally slept, adjusting the lead so that it wouldn’t accidentally strangle her in her sleep.

Sans turned down the lights and slid in next to her, covering them up and pulling her close to his chest as they fell asleep. The next morning she found she’d slept in, laying next to Sans who was still peacefully sleeping in. 

She yawned and found herself curling up next to him, dozing in and out as he wrapped an arm around her lower back, pulling her closer. She normally didn’t sleep in around her master who was an early riser. 

But sleeping up against Sans and his comforting warmth just made her want to relax in bed all day. After a while she felt him stir next to her, Frisk waking along with him as she stretched against him.

“Mornin’.” He yawned looking down at her and she started to sit up next to him. “Actually, it’s closer to afternoon. We’ve slept most of the day away.” Sans watched her through the corner of his sockets as she rolled her shoulders and stretched out her back.


	6. Chapter 6

“Seriously? Man. I haven’t slept that good in ages.” He rubbed his face and rolled over to face her as she ran her hands through her hair, adjusting her collar and letting out her lead so she could walk around.

“I’m going to go the bathroom. But I’m hungry. I don’t usually sleep in this late and I missed breakfast.” Frisk glanced towards the living room, wishing that her Master would return. With a sigh she walked into the bathroom and got ready for the day, walking out to find Sans making something in the kitchen. 

So she took it upon herself to clean the sheets and the clothes from the day before, going into the closet and putting them in the machines there with the soap. She went and grabbed a clean set of sheets and put them on the bed. 

When Sans came in he saw her just finishing making the bed again, fluffing the pillows. “Does he make you do all the cleaning?” He asked as he set a plate of eggs and some fruit in front of her. “No. He’s fairly clean anyways I just want it to look nice when he comes back.” She popped some fruit into her mouth and looked up at Sans.

“Do you know who he used to be?” Sans asked suddenly and she shrugged, shaking her head as she took a sip of some juice. “No. I never even knew his name.” Sans looked at her with concern and she took another couple of bites. 

Sans was quiet as he seemed to be thinking about what he was going to say to her, giving her enough time to switch the laundry over into the dryer. “He used to murder children.” Frisk paused putting the sheets in the dryer at his accusation. “He used to be a scientist for the Underground. The king asked him to find a way to break the barrier. And he killed the children that came here before you in order to do so. Did experiments on them and their souls.”

Sans explained nonchalantly and she frowned, shaking her head as she put the rest of the clothes in the dryer, slamming the door shut and turning to face him with an angry look on her face.

“He’s probably experimenting on you right now and you wouldn’t even know it.” He stood in front of her and she stepped away from him, her good mood completely ruined. “Why would you say that? Why would you say any of that?” She glared, crossing her arms over her chest. 

“Because. You deserve to know. I can take you away from that. Keep you safe. You wouldn’t have to be anyone’s slave. You could be your own person. Live your own life. My brother and I have our own place in town, we can make room for you.” Frisk stared at him in shock and disbelief.

“I’m just as safe here as I am anywhere else! I belong to Master. He cares about me. I want to stay here.” Frisk snapped and Sans tried to reach out to touch her, but she slapped his hands away. “No!” She yelled and heard the familiar click of the lock on the front door.

Pushing past Sans she lunged towards the living room, almost forgetting about the lead tethering her until she pulled it tight. “Frisk? What’s the matter pet?” Gaster asked as he closed the door behind him, coming to greet her, placing hands on either side of her cheeks with concern.

“Did our guest not take good care of you while I was gone?” He rubbed his thumbs over her cheeks as she looked up at him, Gaster leaning down and kissing her tenderly before looking over her at Sans who was fuming.

“You can’t keep her here like some kind of caged up animal. She’s a human not some kind of sex toy you can just hide away. You need to let her go, I can take her to my place and she can live out her life there safely. She isn’t like those humans you experimented on. The humans you killed. You have to tell her the truth and not brain wash her.” Sans glared accusingly at Gaster who ran a hand through Frisk’s hair, resting his hand on her back as she leaned into him.

“I can’t imagine you can really complain when it seems you had your way with her last night. Looks like the pot calling the kettle black if you ask me.” Frisk flinched a little, worried that she was going to get into trouble for sleeping with Sans.

Gaster seemed to understand and rubbed her back comfortingly. “Frisk is allowed to make her own decisions on who she wants to be with and I never once forced her to stay with me.” As if to prove his point he moved her hair aside and unlocked her from her lead, letting it fall to the floor and she looked up at him.

“Yeah and if you haven’t brain washed her already I would actually believe that.” Sans frowned, crossing his arms over his chest, seemingly ignoring the comment about him sleeping with her the night before.

“Frisk. You have to believe me this guy is a child killer. I know what he’s really capable of and you deserve better.” Sans looked at her trying to convince her to come with him. Although his words did strike a chord with her, Frisk still didn’t want to leave Gaster’s side.

“Tell her the truth Gaster. She deserves that much from you at least. You didn’t even tell her your name.” Sans glared back up at Gaster who didn’t seem at all fazed by the shorter skeleton. Gaster seemed to think about it for a moment and Frisk gripped his coat tightly, not wanting to believe that it was true. 

Finally he sighed as he made up his mind, nodding to himself and wrapping his arm protectively around her. “I intend to. But I think it’d be best if you left. Frisk doesn’t seem to want you here and you’re stressing her out. If she decides that she doesn’t want to stay here I’ll be sure to bring her where she’ll be comfortable.” 

Sans seemed about to object but he decided against it, grabbing his clothes from the dryer and disappearing out of sight in a bright flash of blue.


	7. Chapter 7

 

When he was gone Gaster turned to Frisk and gave a comforting smile, guiding her towards the bed, pulling her onto his lap so she was straddling his long body. 

“I’m sorry Master. He wanted to do it and you told me to do what he wanted to do so I did. It was fine until this morning when he started saying all these things about you. I don’t want to go anywhere with him.” She felt tears of guilt rise up as she looked down in shame. “I want to stay here with you.” She felt Gaster lift her chin gently to look at him and he was smiling at her gently.

“Hush my pet. Don’t fret. You’re not in any trouble. Like I said you are free to do as you wish with whomever you wished. Did he force you to do something you didn’t want to do?” He asked softly, his thumb rubbing her bottom lip as she shook her head slowly. 

“No. He was nice for the most part up until a little while ago when he said he wanted to take me away from here.” She explained as he kissed her.

Gaster pulled away and she nuzzled into him, his arms wrapping around her as he held her close to him. She could practically purr with happiness being in his arms again but she could tell that he was thinking about something else. “I need to tell you about my past. It is only right for you to know so that you can be sure you want to stay here. So I want you to listen to me carefully.” 

Frisk nodded as she rested her head on his shoulder. “A long time ago, I worked for the king and queen of the Underground. When monsters were banished down here the humans put up the barrier I was tasked to find a way to get us out of here. By whatever means possible.” He spoke slowly, choosing his words carefully as she listened quietly.

“Through my research I was able to determine that the best way to break the barrier was to use human magic since monsters are not strong enough to compete with a human’s soul. There were children that fell into the Underground over the years. Each one with a special soul, each one a required piece to the puzzle of breaking onto the surface. The king was adamant. The queen was disgusted.” 

Frisk moved so that she could see his face, his eye lights watching her carefully as he spoke. “I needed those children and their souls. I needed to know how they worked, how to break through. I thought there was only one way that I could do that. I was wrong. So terribly wrong in the end.” Frisk blinked as the realization started to hit her of what he was saying.

“I killed them Frisk. And not always was it a quick death. I collected their SOULS to use to break the barrier but after the last one I just couldn’t do it anymore. So, I faked my death and forced myself to live in seclusion for what I’d done. Trying to find another way to break through that wouldn’t use the SOULS of humans.”

Frisk couldn’t believe it. She felt tears welling up in her eyes as she looked at him. Her hands rested on his chest, feeling his own soul slowly pulsing under her fingers through his clothes.

“I understand if you do not wish to continue being here with me.” He looked so sad, his eye lights pale as he looked at her. Frisk didn’t know what to say. She was shocked that he had done these things but she felt that he felt remorse for what he’d done. Her heart went out to him. 

She didn’t want to leave him still. What he had done was horrible, but he appeared to be a changed monster. He was about to speak when Frisk abruptly kissed him passionately, catching him off guard.

He hesitated for only a moment before he kissed her back, hands grasping at her as she started to undress him frantically. Gaster ran his hand over her back, over her ass, inserting his long finger into her core, making her moan into the kiss as she quickly discarded his coat and shirt, fingers desperate to undo his pants, needing to feel all of him. 

Her chest pressed up against his deep violet ecto body, warm and humming with magic. She fumbled with the zipper as Gaster inserted another finger inside of her, curling up and rubbing against her sensitive nerves from within, distracting her from her task. Frisk gasped as he flipped her onto her back on the bed, laying atop her as he ground against her through his pants.

Gaster kissed and licked, nipping down her throat the space between her neck and shoulder, a sensitive spot for her as he pumped his fingers into her, using his other hand to undo his pants, shirking them off to let them fall off the edge of the bed along with his shoes and socks.

Frisk keened as she felt his hardened cock rubbing against her pussy slowly, already wet and ready for him. Gaster lined himself up with her entrance, pushing the thick tip inside of her, impaling her on his shaft to the base.

He waited only a moment for her to adjust before moving again, slow and full of passion as he thrust deep into her. She moaned as she wrapped herself around him, fingers digging into his back, toes curled as he thrust into her. It was hard to know where one ended and the other began as they moved together as one.

Frisk lifting her hips up to greet his thrusts, Gaster’s arms wrapped around her back and waist pulling her as close to him as possible. They moved together as one for what felt like hours, heavy breathing, soft pleading moans and deep groans of pleasure echoing around them in the bedroom.

Frisk cried out for her master, Gaster whispered her name over and over again, caressing her body as she begged for his release. Gaster let loose a deep growl as he came within her, sending Frisk over the edge yet again as his heat filled her up, some spilling out of her and onto the bed sheets under them. Gaster kissed her deeply, Frisk returning the passion as they remained in their embrace, basking in the afterglow.

Gaster remained inside of her, breathing starting to slow from the long session, kissing up and down her neck, back up to her lips slowly, Frisk returning the gesture more than happily. 

“Frisk…” He whispered into her skin softly, the tone in his voice so different from all the other times she’d heard him. It was then she knew, that feeling in her chest that’d been growing every day she spent with him.

But still she felt a strange sense of uncertainty as she looked at her master. “I never want to leave you. I-“ She started, biting her lip when Gaster turned his gaze on her, looking at her with a soft smile.

“What is it my dear? You can tell me.” He whispered, brushing a hair from her face as he looked at her tenderly. Frisk gathered her courage, taking a deep breath and feared the rejection of her words she was about to speak. 

“I-I love you. I love you master. I want to stay with you always.” She breathed, the tears starting to well up in her eyes as he looked down at her in surprise. Then his look softened, kissing her sweetly, one hand cupping her cheek.

He pulled back, just barely so that their mouths brushed against one another. “I love you too my pet. My good, sweet girl. My love.” She let out a sigh of relief, a grin breaking out over her lips as happiness filled her up, kissing him again. They spent the night interlocked with one another, touching and kissing, whispering to one another sweet nothings.


	8. Chapter 8

The next few days were spent with the two of them being nearly inseparable from one another. One morning she woke to find him lying up against the headboard reading an old looking book and sipping his cup of coffee. 

“Good morning. Sleep well?” He asked looking over at her when he realized she was awake and she nodded, stretching beside him as he put down his coffee and leaned over to give her a good morning kiss.

She rested her head on his lap as he went back to reading, a soft smile on his face as he ran his fingers through her hair idly. It was peaceful. Frisk was happy. Gaster seemed pleased as they fell into a routine together. 

After a little while Gaster pat her gently on the back, Frisk getting up off of him and watching him get up from the bed. “You hungry little one?” He asked and she got out of bed, following him into the kitchen, helping him prep our breakfast in tandem with one another.

After breakfast she got dressed into one of her favorite sweater dresses, joining him on the couch with a book, leaning up against him while he turned on some music for back ground noise. They sat there reading together in comfortable silence, the sound of the soft music and pages turning the only noise in the small home.

The silence was broken when there was a brilliant flash of pale blue magic, revealing Sans standing there glaring at the both of them dangerously. “Sans. It’s not very polite to just barge into someone’s home uninvited.” Gaster spoke calmly, closing his book and setting it on the coffee table in front of him while Frisk sat up, glaring right back at Sans.

“I knew you didn’t tell her anything. So, I’m going to get her away from you before you screw her up even more.” Frisk practically snarled as she went to stand, her fists clenched at her sides. Gaster grabbed her hand gently in his as he stood beside her, holding her hand in his. “I did tell her and she made her choice to stay. So I don’t think you’re going to be taking her anywhere.”

Sans directed his anger up at him and took another step forward, eye lights flashing in rage. “I highly doubt that. Otherwise she’d be long gone by now.” Frisk rolled her eyes and found her courage standing next to her master and her love. 

“He did tell me. He told me the whole story. And I’m staying here. I’m not going anywhere with the likes of you.” She explained, leaning into Gaster’s side. “She made her choice. Now please leave.” Gaster gestured towards the door but Sans was having none of it. He didn’t seem the least bit convinced at their words as he glanced between the two of them.

“Not without her.” He moved so fast, wrapping her up in his arms before she could react, surrounding her in a brilliant blue light, Gaster’s presence torn away from her. When the light cleared she found herself a little disoriented, blinking away the spots on her eyes as she tried to register what was going on. 

“There we go. Now you’re safe.” She heard Sans’s voice sounding proud of himself as he rubbed her arms gently. “Where am I? Where’s Master? What have you done!? Take me back!” She yelled as she looked around, searching for Gaster in the well-lit cabin like two level home.

“He can’t hurt you here. You don’t need to call him or anyone else Master anymore. You’re safe Frisk.” Sans smiled and she moved to swing at him, the skeleton dodging her hand easily.

“Safe?! Are you kidding me! I want to go back to him! What part of I don’t want to be with you don’t you understand?!” She yelled angrily, swinging at him again and again but none of them hit him at all which only made her more frustrated. 

“He’s brain washing you! He doesn’t deserve you! You don’t deserve to be treated like that!” He yelled back, grabbing her as tears ran down her face, screaming as if in pain as he held her, shushing her as she sank to the floor.

“It’s ok. You’re going to be ok. He can’t get to you here. I made sure of that.” He whispered and she sobbed, trying to pull away from him as she let out a mournful scream.

“It’s ok. You’re going to be alright. I promise to keep you safe.” Frisk cried as she felt the hopelessness overtake her. Several hours later when she had stopped crying, Sans was sitting on the couch watching television while she sat on the ground about a foot or so away. 

She gathered her courage and rushed towards the door, grabbing the handle and trying to pry it open only to find it stuck tight. “You can’t get through unless you’ve got a key.” Sans pulled out a pale blue key from the depths of his coat pockets, holding it up from his relaxed position on the couch. Frisk gave a frustrated groan as she slammed against the door harshly.

“Look you’re not going back to him. He’s got you all twisted up in the head and it’s going to take time to get you back to where you were before you met that monster. You’re going to probably go through withdrawals but I’m here for you and I talked to my brother about it so he’s going to help out too.” 

He watched as she began pacing like a caged animal, her eyes darting around to find a way of escape. “Withdrawals? There’s nothing wrong with me! The only thing twisted up is you!” Frisk growled, launching herself on him much to his surprise as he grunted softly as she collided with him.

She tried to hit him, tears falling again from her eyes as he grabbed her hands and kept her from hitting him. He looked up at her with pity before he flipped her over onto the couch, pinning her under him. 

“I love him! And he loves me! And you stole me away from him! We aren’t hurting anyone or even bothering anyone and yet you…” She cried, glaring up at him as he held her wrists above her head on the couch. “It isn’t love Frisk. He’s manipulated you and your emotions into thinking that you do. What about you giving me a chance? Hell even my brother would be a better choice than Gaster. At least we will treat you with respect. We can take off this collar-“ 

Frisk freaked out when he reached for her collar, her body going into panic mode and he pulled away. “Alright, alright. We’ll leave it on until you’re ready to take it off yourself. Are you hungry? I could ask Papyrus to bring something home?”

Sans asked as he got up off of her, letting her curl up in the corner of the couch, ignoring her. Sans sighed and sent a message on his phone from the other side of the couch.

Several hours later the front door opened and quickly locked after it was closed. There was a tall skeleton wearing some sort of armor and a bright red scarf, holding a couple bags in his gloved hands. “Hello brother! I’m home! I brought dinner for you and our guest.” 

He took off his boots at the door and turned to face her and Sans on the couch. “Hello human. My brother said that you were going to be staying with us for a bit and that you weren’t feeling well. But have no fear, the Great Papyrus will nurse you back to perfect health!”

Frisk stared at him, seeing a slight resemblance between him and her master, at least in the height and the way he looked at her with kindness. “I brought you some soup. Are you hungry?” Papyrus asked and she frowned, ignoring him and curling up tighter on the couch, her hand tight around the tag of her collar as she longed to be back home. 

“Just give her some space bro. She’s been through a lot today.” Sans sighed, getting up off the couch and following his brother back towards the kitchen to get things ready to eat.

Frisk ignored them as they ate at the table behind the couch, talking quietly among themselves. Before she knew it she found herself waking up sometime during the early morning hours the next day. 

She had a blanket and a couple of pillows that weren’t there when she’d fallen asleep as well as a glass of water and a note saying that there was food in the fridge for her to help herself if she was hungry. 

She was hungry, her stomach grumbling as she got up and stretched, looking around for signs of the brothers.

There wasn’t anything but the doors upstairs were closed so she assumed that they were still sleeping. With a heavy sigh she looked forlornly towards the locked front door and the thick glass of the windows before heading into the kitchen and making herself the soup that had her name written on it. 

While she waited for it to warm up in the microwave she heard a door open upstairs, a moment later she saw the taller skeleton walking in to the kitchen. “Oh! Good morning human. I hope you slept well. Can I make you some breakfast?” He asked as he got some eggs out of the fridge and went to the stove.

She didn’t say anything, unsure how she should act around him just yet. He smiled politely at her and shrugged as he started to make something to eat. 

“You know my brother has a good heart. He told me the story about your collar there and he said that you’ve been through a lot. I agree with him in that you should stay here for a little while at least. Even if I don’t agree how you got here I think it might give you a chance to breathe. So you ask me for anything and I’ll make sure you’re taken care of.” Papyrus smiled up at her as she watched him plate up his meal, gesturing for her to join him at the dinner table when her soup was finished.

She felt a sort of familiarity with Papyrus that echoed that of her master. In a strange sort of way it comforted her and she joined him at the table. “I do have to warn you though.” He said between bites, a faint orange blush on his cheek bones. 

“Heat season is coming up for my brother and I so I apologize in advance for the crudeness you may experience. We can put you up in the small shed next door, it has warmth and we can put a bed in there for you. There’s even a window and plenty of room for exercise. If you decide to stay we can make it your own.” Frisk ate some of her soup and tilted her head to the side in confusion.

“Heat? What’s that?” She asked quietly, her voice a little sore from the previous day’s yelling and crying. Papyrus cleared his throat and finished off his plate. “It’s a sort of mating season for monsters. Each one has a bit of a different time frame but for us skeletons ours is coming up in the next day or so.” Frisk nodded as she understood what he was talking about, having read about it during her time with Gaster.

But his offer to have space away from Sans was tempting. “I’ll take you up on your offer.” She stated as she finished her soup and Papyrus stood to grab her bowl from her, their hands touching and she felt his magic respond before he collected himself and cleaned the dishes.

“Good. I’ll get my lazy brother to help me out getting it ready for you. For now if you want you can sleep in my room, there’s a bathroom and everything in there.” He gestured towards the room upstairs and she nodded. 

“Thank you.” She spoke softly as she headed up there, closing the door behind her while she heard Papyrus going into his brother’s room next door.

She was able to clean herself up in the bathroom and fix her hair, going about her morning routine when she heard the front door opening and closing, leaving the house completely silent.

She began to explore, not used to having all of this space to herself. Papyrus’s room was neat, much like Gaster preferred, with the bed made, everything free of dust. 

Next she went to check out Sans’s room but it was locked so instead she went back to Papyrus’s room and lay on his bed, feeling a little bit frustrated, missing her master more and more every second.

Before she knew it she had dozed off again, stirring when she felt a hand run up her leg slowly, her mind still fuzzy with sleep as she smiled. “Mmmm.” She hummed as she felt someone sitting next to her on the bed. 

“master…” She breathed, turning over and opening her eyes to find Papyrus there instead of her Master. His face flushed pale orange, so close to hers, his soul shining through his shirt in arousal. 

Once her eyes met his he seemed to collect himself, pulling away from her with a look of shame on his face. “We got your place set up for you. You ready to go?” He asked as he cleared his throat.

She got up, their faces close together, leaning in and kissing his cheek bone softly which made him flustered as Sans came in, hands in his pockets. “Come on. I’m just gonna teleport us there to save us te trouble of having to chase you down in case you try and run off.” 

Sans placed a hand on their shoulders, blinding them with magic for a moment before they were in a small single room building. Frisk adjusted to the light, blinking away the blinding blue of Sans’s magic. When her vision cleared she blinked in surprise.

There was an extremely large bed, as large as Gaster’s bed, covered in deep red blankets that looked comfortable and soft. There was a large matching cushioned chair that looked a little strange to her as there were a couple rings attached at the corners as well as only one cushioned arm.  

There was a plus rug covering the wooden floor with a lattice pattern woven into the fabric, string lights gave the room a soft pleasant glow. There was even a large dresser and matching mirror in one corner, right next to a curtained window. 

“What do you think? Do you like it?” Papyrus asked and strangely enough she did. She found the aesthetic pleasing and she went to check it out. The room was warm, keeping the chill of the eternal winter at bay.

“Yes. It looks very nice. Thank you.” She gave a charming grin that caught Papyrus off guard. “Good. I’m glad you like it. Sans picked out that strange looking chair though. He said it looks nice and that it was comfortable.” 

He smiled down at her, his eyes trailing over her as she went to inspect the couch, running her hingers over the almost black wood. “We can still bring you food but for the next couple of weeks we may or may not be able to spend a whole lot of time with you because of the heat. Already I can smell your pheromones and they’re making my head spin.” 

She turned and sat gracefully on the loveseat, crossing her legs over one another and looking up at the skeleton brothers who were both flushed, their magic manifesting their ecto bodies under their clothes.

She could smell the strange sparking scent of their magic that made her think of Gaster. She felt her trained response starting to kick in and she fidgeted in her seat.

Papyrus cleared his throat and placed a hand on his brother who seemed to jump at the contact, breaking his gaze on her. “W-we’re going get let you get settled in for now.” Papyrus guided Sans out of the room, both of them looking tense.

When she was left alone she tried to get through the window, finding it sealed shut and the glass thicker like the ones in the main house. The front door was also locked as she sighed with annoyance.

She wanted nothing more than to curl up with her Master, feeling his hands over her. Taking her over and over again. She flopped onto the bed, hopelessly aroused from the combination of the brother’s magic and her own needs. Frisk refused to touch herself though, that was part of the rules her Master had laid out for her during her training.

She tried to calm herself, counting the snowflakes falling outside the window from her new love seat. The cushions were comfortable and she wondered where they had gotten everything in such a short amount of time. 

After a few hours she was still left wanting but she had managed to keep her cool, the want just barely simmering under the surface. She took a deep, shaking breath as she began to undress, feeling better, more confident without the fabrics against her skin. 

As she let her sweater dress fall to the floor she heard a soft growl behind her. “I’ve been looking for you my pet.”


	9. Chapter 9

Frisk gasped and turned to see her master standing behind her, face flushed deep violet, his breathing heavy as his tongue manifested to run across his teeth. “Master! You’ve found me!” She breathed, body practically crying out for him as she ran to embrace him. Gaster lifted her up, her legs wrapping around him as he brought her face to his in a deep kiss. 

“How did you find me?” She whispered as he guided her to the bed, his body hot against hers as he ran his hands over her skin hungrily. “I caught your scent as the others left. There is no way I’m going to allow my younger brothers to take you from me.” He growled as he moved atop her, practically ripping off his clothes as he nipped her throat, fangs dangerously close to piercing her skin as she gasped.

“I need you. I need all of you. Now.” He growled into her skin. He grabbed her hips, lifting them to position himself at her already slick pussy, his cock stiff and twitching. “Master…please! Don’t tease.” 

She begged and he slammed into her, a keening moan of pleasure mingling with his deep groan. He was desperation and need, a wild hunger like she’d never felt from him before. She lost all sense of herself as he took over, pinning her down, slamming so hard into her she knew she was going to be sore in the morning. All the while his body radiated heat in waves as he growled, fingers gripping her tightly.

She cried out as she climaxed hard around him, her body trembling as he pummeled her into the mattress. She was lost in a haze of pleasure as Gaster continued to thrust hard into her. 

After what seemed like ages, he finally let loose a long, deep groan/growl as he came hard inside of her, spilling his hot seed, filling her to the brim and then some. Gaster rolled off of her, his eye lights hazy as he panted from the exertion. Frisk lay spent as she glanced over at her master lovingly.

“I’m sorry love. I’m not fully in control of my actions for the next few weeks.” Gaster breathed, one hand reaching up to brush her cheek as she rolled over to him. “You’re in heat. It’s understandable. I’m just happy to be with you again.” 

She purred, leaning into his touch, Gaster kissing the top of her head as they lay together. “Do you understand what it means for a monster to be in heat? In it’s entirety I mean.” He asked softly and she looked up at him.

“Not really. Just that it means your mating season has started really, heightening your senses to find a suitable mate.” She responded softly as his gaze turned to her once again.

Gaster took a shaky breath, closing his eyes a moment as if to collect himself before speaking again. “It means that I’m a slave to my own desires. My baser instincts will be in control and you’ll more than likely be at my mercy. I need you to understand that.” 

She managed to lift her head to look down at him on the bed. “I’ve always been at your mercy. That isn’t going to change now. I love you Master. I’m yours, body and soul.” She whispered, kissing him deeply.

He groaned into the kiss, fangs brushing against her lips. “It seems my brothers have also entered their cycle early this time. I could smell them from a mile away.” Gaster pulled her atop him, Frisk laying on his chest as she looked at him curiously. 

“Brothers?” She asked with a frown. His hands ran over her back, heavy handed as she felt him hardening against her again. “Yes. I raised my younger siblings since the day they were born. Although I am far older than they are. We came to the Underground much in the same way you did in fact, as a way to get away from the humans at the time.” 

He breathed, closing his eyes as he moved under her, rubbing between her thighs. “You…smell so…mmmmm” He growled, licking her jaw slowly.

“Frisk…I…really don’t…I can’t control myself around you…” He kissed her passionately, taking her breath away, Frisk straddling him. “Then don’t master. I’m yours to use for as long as you need me. I love you.” 

She kissed him again, kneeling between his legs and taking his shaft in her hands. Gaster sat up, looking down at her as she stroked his shaft, using her tongue, licking and sucking. Gaster grabbed the back of her head, thrusting into her mouth, a groan thick with passion rumbling through him.

“That’s my girl. My good girl.” He praised as she hummed around the shaft in her mouth, his hand gripping her head tighter at the sensation. “Play with yourself pet. Pleasure you as you pleasure your master.” 

He ordered and she obeyed. Running her fingers over her body, rubbing her clit as Gaster thrust into her mouth. They were so absorbed into one another that they didn’t hear the door opening and closing.

“Frisk…hnnnn…That scent…ahhh…” Papyrus’s voice moaned, making Gaster growl, releasing her as she came up for air, licking her lips as she looked over to see Papyrus practically panting, tongue running over his teeth. 

“She’s mine.” Gaster growled dangerously, his cock twitching in front of her, Frisk licking it slowly from the base, swirling her tongue around the tip, turning her gaze back to her Master who was breathing heavily with need. 

“B-but she smells so good…I-I can help her…hah…it hurts I need it so badly…” Papyrus took several steps forward as Frisk took Gaster yet again into her mouth sucking and licking while playing with herself, inserting her fingers into her wet pussy.

He hadn’t told her to stop after all. Gaster groaned once again grabbing the back of her head as he thrust into her. “I need…her…” Papyrus groaned as he came to stand behind her reaching to touch her shoulders, being stopped by Gaster’s strong grip.

“Frisk…love…nnnngh…spread your legs…” He ordered, violet eyes sparking with magic as she obeyed him, hearing Papyrus’s pants hit the floor. “Let him take care of you…I want you to feel as good as you’re making me feel right now…” Gaster locked eyes with her, moving his hand to grip her chin as he thrust into her mouth.

“Frisk…nyeah…I want you to feel so good…” Papyrus breathed, the tip of his cock teasing against her entrance, slipping between the folds as she let out a soft moan, the vibrations making Gaster thrust deeper into her throat.

She was still sore from the previous session but she would obey her master no matter what. Papyrus teased her entrance, fingers running over the ridge of her spine over her skin, positioning himself behind her as he ran his hands down to her hips. 

She nearly choked on Gaster’s cock as Papyrus penetrated her with a long keening moan. He was so long, so thick his cock shoved so deep she felt so full. “Isn’t she such a good girl? You’re my good girl. Taking two big cocks like this…” 

Gaster praised, making eye contact with her as Papyrus moved inside her, fingers digging into her hips as he started thrusting into her, each thrust pushing Gaster’s shaft down her throat.

“Yes she is a good girl. So good…so soft.” Papyrus breathed, leaning over and kissing between her shoulders. Frisk moaned as he thrust into her, her body hot as the skeletons heat rushed over her from both sides, heating her up within.

Papyrus thrust harder and faster, shoving Gaster’s thick shaft down her throat, almost making her gag, his fingers tangling in her hair, holding her in place. “Hahhh…hnng! Stars I’m so close! Frisk! You’re so good! Good girl! I-I-ahhh!” 

Papyrus moaned, pumping into her wildly as he climbed to his climax, Frisk reaching her third or fourth one already, her legs drenched in fluids as Gaster held her in place, just starting to go over the edge as he grew inside of her mouth, “My good girl…so good my pet!” 

Gaster growled as he came suddenly, his hot seed running down her mouth, some of it seeping out of her lips as she climaxed again, pulling away to cry out in blissed out pleasure, Papyrus burying himself deep inside of her as he came, filling her up just as Gaster had before.

Papyrus remained inside of her as he began to come down from his climax, his skull resting in between her shoulders as Gaster ran his hands through her hair, leaning down to kiss her passionately, not seeming to care about tasting himself as their tongues danced around one another. 

Finally Papyrus pulled out of her, letting their fluids drip down her thighs, orange mixing with violet and the clear of her own. Without him holding her up her legs gave out on her and she faltered.

“Poor girl…you’ve done so well…come and rest for a while, we’re going to need you again soon enough.” Gaster grabbed her, helping her up onto the bed and covering her up. 

“Papyrus and I will keep you nice and warm, won’t we brother?” Gaster turned to Papyrus who was still a little blissed out but he nodded as he climbed into bed on her other side, Frisk curling up to Gaster and Papyrus pressed against her back, their combined warmth soothing her sore muscles as she was lulled to sleep by their combined breathing.


	10. Chapter 10

By morning the three of them were tangled together in one mess of limbs, Frisk sandwiched between them as she began to stir, feeling movement from behind her, a soft moan of coming from Papyrus. 

The warmth of both monsters having soothed her sore muscles throughout the night. Frisk gasped as she felt Papyrus enter her, thrusting slowly as his hands wrapped around her middle and pulling her closer to him. 

She was barely awake as she glanced over her shoulder, seeing Papyrus still asleep as he thrust inside of her, her soft moans making Gaster stir.

“Hush my pet. Let him, that look on your face…so precious…” Gaster whispered, grabbing her hand and wrapping it with his own, stroking it slowly, leaning in and kissing her deeply, smothering her moans as Papyrus fucked her in his sleep. 

Frisk arched her back, Gaster moving from her lips to lick at her hardened nipples, his other hand rubbing against her clit making her moan in pleasure.

Papyrus thrust deep inside of her, grunting in his sleep as his pace picked up, his cock growing within her tight pussy. 

“That’s my girl, take his cock like a good girl. Tell me you like it. Tell me you like him pounding you in his sleep.” Gaster breathed, using her hand to jerk him off while he rolled her sensitive nub, nipping at her breast. 

“Master…I like taking his cock in front of you…hnnng! Master I’m going to cum! He’s so deep inside of me!” She keened and Gaster growled with satisfaction, moving to her lips again in a fervent kiss.

“Don’t come pet. I don’t want you to come just yet.” He breathed as Papyrus groaned in his sleep, thrusting wildly, Frisk feeling he was close as he grew inside of her. 

“If you come you’ll be punished, understand?” She nodded, wanting desperately to release but she did her best, biting her lip as Gaster pinched her clit between his fingers, his breath on her throat as Papyrus thrust into her. Finally Papyrus climaxed, filling her up again, heating her up inside as she tried desperately not to come.

“Good girl, clean him off.” Gaster ordered and she pulled herself off of him, moving down to take Papyrus’s still hard cock in her mouth licking their combined juices off of him while Gaster positioned himself behind her, impaling her on his cock and pounding into her. He leaned over her, biting her shoulder as she took his shaft.

Papyrus groaned as he started to stir, his cock twitching in her mouth as she cleaned him off, sucking and licking as she’d been trained, moaning as Gaster thrust into her.

“Mmmmm…yes hnnng! That’s…so good human!!” Papyrus praised and she felt a sense of pride rise in her, the same as whenever Gaster would praise her. “You can’t come until you make him come again…I want to see his semen all over that precious face of yours my pet.” Gaster nipped her ear, one hand rubbing her clit as he thrust into her. 

She gave a soft whine as she almost came right then and there, the sound of his voice at her ear, the feel of his hand, his cock, even Papyrus’s cock making her want to let loose.

Papyrus thrust into her mouth, panting heavily as she was pounded harder and harder. Gaster slammed into her, hitting her g-spot over and over, her body no longer able to obey as she came hard around Gaster’s shaft, a growl as he felt her clamp down around him.

“Oh my pet. You disobeyed me…you’ll be punished for that.” Gaster thrust harder into her, forcing her down on Papyrus’s cock as he groaned, Frisk nearly gagging on Papyrus.

Papyrus came first, spilling down her throat with a loud moan, holding her head down as far as she could take, the sight causing Gaster to follow quickly with a deep growl. Both of them pulling out of her on Gaster’s command.

“Clean me off pet.” Gaster stood by the edge of the bed, Frisk obediently crawling over to him on shaky limbs. Papyrus moved to follow her but Gaster waved him off. 

“No. She’s being punished for disobeying.” Papyrus watched hungrily as she cleaned off Gaster’s shaft, Gaster grabbing her by the hair and pulling her off of him and forcing her to look up at him, a mixture of his and Papyrus’s seed dripping off her chin still.

“You’re not allowed to come for the rest of the day now pet. I’ll return with your gear and something for you to eat. Be good while I’m gone. Papyrus.” Gaster turned his gaze to Papyrus while Frisk knelt on the bed obediently. 

“If I’m not back and you feel the need, use her mouth.” Gaster pulled on his pants and shoes, leaving without looking back and closing the door behind him.

“Frisk?” Papyrus moved behind her, reaching out to touch her shoulder. “I-I didn’t mean to…” He started but she shook her head, turning to face him with a soft smile, leaning up to him. 

“Don’t. There’s nothing to apologize for. I am back with my master. And you…you are so much like him. I’m happy.” She curled into him, his arms wrapping around her after a moment of hesitation. 

“But you’re getting punished. Isn’t that a bad thing?” He asked and she shrugged. “So long as I’m good eventually I’ll be rewarded again. His punishments are not always as punishing as you might think.” She smiled, closing her eyes as she felt his warmth around her.

They sat like that for a little while before Papyrus was overcome with need again. Frisk obliged, kneeling in front of him on the bed as he groaned, tongue lolling out of his mouth as he thrust into her mouth.

“Paps? Where are you?” Sans called out, Papyrus not stopping as his brother came inside. “What the-?! Fuck…the smell is so strong…” Sans’s knees practically buckled as her scent assaulted his sensitive nose. 

“Don’t stop Frisk…you’re so good…a good girl…” Papyrus breathed as she did as she was told, looking up at him as he shoved his cock down her throat. 

“Damnit bro…that’s unghh…she smells so good…” Sans’s eyes practically rolled to the back of his head as he groaned, walking towards them on the bed as if a moth to a flame.

Just as he came to the side of the bed Gaster returned, a bag slung over his shoulder as he walked in, seeing Sans’s surprised face, Papyrus still thrusting down Frisk’s throat, groaning in pleasure.

“Frisk. Go sit on the chair.” Papyrus gave a soft whine as he let her go, slowly stroking his shaft as he sat back on the bed to watch her. “You’re not supposed to be here! How’d you find-“ Sans began but Gaster just walked right past him, setting the bag on the floor and kneeling in front of Frisk. 

“Her scent is strong. It was a matter of time before I would find her again. Spread your legs my pet.” Gaster pulled out some black rope, taking one of her ankles and tying it to a leg of the loveseat, doing the same to the other, each time running his fingers over her sensitive skin, teasing and playing.

“Lean forward.” She did as she was told as he tied her wrists behind her back, attaching the rope to her collar from behind, which put a slight pressure on her throat.

“Wha-what’re you doing? You can’t do that to her…even though she looks…hah…” Sans groaned as she felt her master tie her hands down so she couldn’t move at all except in small amounts to relieve the pressure on her neck. 

“How does she look Sans? Delectable? Vulnerable, completely at our mercy. For our pleasure.” Gaster leaned up and kissed her, “are you comfortable my love? Not too tight I hope.” He asked in a whisper, hunger in his eyes. “Yes Master. I’m ready for my punishment.” He smiled as she licked the side of his face with the tip of her tongue.

“You remember the safe word?” She nodded, feeling his hand slide up her thigh. “Sans. Come here.” Gaster called over his shoulder, Sans hesitating a moment, the heat overtaking his better judgement as he stood next to Gaster, looking down at her with a lust filled gaze.

“Grab one of the toys out of the bag, anything you’d like. And I want you to use it on our lovely little pet.” Gaster kissed her again as he stood, standing behind Frisk with his hands on her shoulders, Papyrus came to stand just behind his brother, watching her while his shaft twitched eagerly.

Sans looked through and found a large glass dildo that had large bubble like ridges on it. “Good choice. Papyrus. Let her take care of you some more.” Gaster took control of the room, Papyrus placing a knee on the love seat and Gaster guided Frisk’s head to take Papyrus’s shaft in her mouth, the collar putting pressure on her throat, lightly choking her as Papyrus resumed thrusting into her throat. Sans inserted the dildo, making her moan softly as he started pumping it in and out of her in time to Papyrus’s thrusts.

Gaster moved to the bag, pulling out a couple of nipple clamps that were attached to thin silver chains. With one end he hooked it to the front of her collar, he teased her nipples with his hands before gently clamping them, making her wince slightly with the hint of pain but she didn’t complain, the mix between pain and pleasure was one of the things she found she enjoyed.

“Sans. Fuck her.” Gaster growled, standing on the opposite side of her, mimicking Papyrus’s pose as he shed his clothes, his cock ready and twitching for stimulation.

Papyrus pulled out of her mouth, stroking his cock as he watched her take Gaster in her mouth, Sans kneeling between her legs as he replaced the dildo with his own throbbing shaft with a groan of pleasure.

Frisk went between pleasuring Gaster and Papyrus, moaning as she felt Sans pounding into her core. She was so close, Gaster noticing and ordering Sans to pull out just as she started to climax, denying her release. 

Gaster grinned down at her as she gave a whimper without thinking. “Wear that ring Sans. Then you can stop whenever you want without worrying about coming inside of her.” 

He pointed to a black rubber ring, Sans not hesitating as he pulled it over his shaft, rolling it to the base and going back to pounding into her as she resumed pleasuring Gaster and Papyrus.

Frisk felt tears of frustration sting her eyes as she received another string of cum to her face, joining the other streams of violet and orange, even some blue that dripped down over her chest.

Sans knelt at her side, panting as he reached another climax, painting her with more pale blue. Gaster knelt between her thighs, a pleased smile on his flushed face.

“Do you want to come my love?” He asked as he turned the vibrator back on, moving it slowly within her, building her back up again as she struggled to gain more friction, anything to bring that sweet release.

Papyrus was readying for another round, Sans slowly working himself up again as well, leaning back on the love seat as he found pleasure in watching Frisk squirm hopelessly. 

“Y-yes…please…” She whimpered as she started to get close again, Gaster noticing and turning it off again, making her strain against the restraints as the tears started to fall out of frustration, streaking through the layers of semen. 

“Do you really? Beg.” Gaster palmed his own erection, brushing it against her highly sensitive pussy, teasing almost painfully as she keened desperately.

“Please. Please let me cum master…Please! I need to cum!” She begged, shaking as she looked at Gaster pleadingly. “I don’t know if you’ve learned your lesson yet. Perhaps we should ask for another opinion.” Gaster chuckled, teasing her some more, Frisk arching her back with a long moan. 

“Please…Masters…p-please…” She begged, pleading for release. Papyrus grabbed her head, shoving his cock in her mouth again with a low groan, magic beading on his ecto flesh from the long hours of using her over and over again.

“What do you think Papyrus? Do you think she learned her lesson yet?” Gaster removed the vibrator, teasing her with the head of his shaft as Papyrus thrust fast and shallow in her mouth as she moaned around him. 

“Nyeahhhhhhh…she’s been such…stars…such a good girl! Hah…such a good girl! I think she’s learned…nnnggh her lesson…” Papyrus wiped away some of the semen from her face before it got into her eyes, wiping it on her shoulder as he kept thrusting into her throat.

Gaster added more of his cock inside of her, moving very little, keeping her just below her plateau. “Sans? Has she earned release?” He turned his attention to Sans who was lost in bliss as he watched her, stroking himself vigorously, hips bucking into his hand.

“More than earned it. Fuck…let her cum.” Sans groaned, eyes glued to her pussy as Gaster smirked. “Seems you’ve earned it my love. Now it’s your turn. I want you to cum with me. Come with me my pet.” Gaster thrust into her, impaling her balls deep, Frisk nearly choking on Papyrus as he took her mouth as deep as she could.

Papyrus came as she swallowed reflexively, the sensation driving him over the edge, some of his hot seed leaking between her lips as she cried out loudly in pleasure, Gaster leaning over her, hands gripping the back of the love seat and staring at her as he thrust deep inside. 

Sans picked up his strokes as he watched her pussy get pounded, rocking the love seat with the force of Gaster’s thrusts.

“Scream for us my love. I don’t want you to hold anything back.” Gaster breathed as she felt him starting to reach his climax. She was so close, toes curled tightly, back arched as she felt it coiling tightly within her. 

Her cries of pleasure reached heights she’d never felt before, her brain turned to mush from the over stimulation. “Come. Now. Come for you master. Come for your love.” Gaster breathed into her ear, sending a chill down her spine as she felt a round hard knob work past her folds, the sensation joining pain and pleasure as it stretched her insides. 

Frisk felt the coil come undone, her voice crying out as she came hard around the strange knot of Gaster’s cock, Gaster thrusting wildly as Sans came on her with a loud groan. Frisk lost all power of thought, still riding her high as Gaster thrust, his motion somewhat restricted by the knob.

“That’s my good girl. Tell me you love me again.” He whispered, breathing heavy as he staved off his climax till that last possible second. “I love you. I love you, I love you.” She moaned, looking up at him through hazed out eyes. Gaster wiped her mouth roughly, kissing her passionately, pouring all his emotions into her as he bucked into her, groaning against her lips as he came hard, spilling his seed deep, deep inside of her, sending her over again.

Frisk practically collapsed against the back of the love seat in exhaustion. Gaster still locked inside of her as he let out stream after stream of his seed inside, filling her up, the strange knob keeping it all inside as he panted, hips twitching with each release.

“I love you pet.” He mouthed against her lips and she kissed him in response. Sans was out cold, Papyrus mostly gone as he lay on his back on the bed. After what seemed like ages, the knot finally was small enough to allow Gaster to pull out, Frisk suddenly feeling almost empty again without him inside.

“I think that’s enough for today. You need a bath. And probably something to eat.” Gaster untied her, removing the clamps and catching her as she almost fell into his arms. 

Outside it was night, Gaster using a sheet to cover them up and putting on his shoes as he walked them out the main house as she leaned into him, completely content. Gaster lay her against the tub, tossing the sheet aside as he turned on the water. When it was half way full he placed her inside, holding her up as he carefully cleaned her off, Frisk already half asleep as it was.

When she was cleaned from head to toe he got in and cleaned himself off, showering her with kisses and gentle touches, whispering sweet words to her. 

“Come on my love. You need to eat a little bit before I let you go to sleep. I brought some fruit.” Frisk nodded slowly in understanding, allowing him to dry her off and take her to the couch, going to the kitchen and returning with a small bowl of her favorite fruit.

“Eat. You’ve done a good job today my dear. Very good.” He smiled, Frisk eating slowly, her mouth sore from the day’s events. She managed to finish of the bowl and yawned as she leaned into Gaster on the couch.

They sat there for a moment before Sans and Papyrus shuffled in, barely registering that they were there except for Papyrus telling them he’d clean the love seat in the morning before they went up to their rooms.

Gaster carried her back to the shed, his warmth keeping her from getting cold in the short trip back to the shed. He closed the door and took her to bed. He covered them up under the warm covers and held her close to him. 

“Tomorrow you should rest. You deserve it and I think you managed to sate all of our needs for a little while. I’ll take care of you. I’ll always take care of you.” She nuzzled into him, smiling as she started to drift off. 

“You’ll have to tell me about that strange knot thing you did Master. It was…good…” She fell asleep before she could see the look on Gaster’s face, the look of surprise and a hint of guilt. 

“Yes, my love. I’ll tell you all about it. But for now, just rest.” He kissed her forehead and held her close, falling asleep next to her shortly after.


	11. Chapter 11

Most of the next day Frisk laid in bed, curling around Gaster whenever she could. “Come on darling. I have to clean up, we can’t just lay in bed all day. At least I can’t.” Gaster chuckled, kissing her pouting lips and untangling her from him. 

“I know, you’re just so warm.” She yawned as Gaster tucked her in, Papyrus walking in a little stiffly with a basket of cleaning supplies. “Good morning you two. How are you feeling Frisk?” He smiled as he came to Frisk’s side, smiling at her pleasantly. 

“Just a bit sore but I’m alright.” Papyrus tucked a hair behind her ear and she snuggled into the warm blankets, yawning. “You better not fall back asleep, I need you to eat something today since you didn’t eat hardly anything yesterday.” Gaster winked as he and Papyrus went about cleaning up and sterilizing the toys that’d been used the night before.

Frisk, gave a soft groan of annoyance but she stayed awake, watching them through half closed eyes. “Where’s Sans?” She asked, turning on her side to watch them. 

“Oh, I think he’s still passed out. He doesn’t have the stamina that we do and yesterday pretty much wiped him out completely. I don’t expect him to wake up anytime soon.” Papyrus smiled up at her as he wiped up the floor, Gaster getting dressed in some clothes he’d brought with him in the bag. 

“Since you took such good care of us yesterday, the boys and I will take good care of you today. After all,” Gaster sat on the bed next to her as she looked up at him, “we have to be responsible with our pets.” She smiled, kissing him passionately, his long fingers playing with her collar as she looked up at him lovingly.

“I’ll bring you something to eat. I don’t want you moving out of this bed unless you have to today.” He smiled, getting up and following Papyrus outside, closing the door behind them. 

She wasn’t waiting long before Gaster returned but she could also sense that there was something on his mind as he sat next to her on the bed with his own plate of food. She watched him carefully as she ate, seeing him eat slowly, his mind turning over. “Master? What’s on your mind?” She asked and he looked over at her.

Gaster cleared his throat as he thought for a moment. “It’s nothing my love. I just hope that I didn’t hurt you yesterday when…” He shook his head and sighed, Frisk putting aside their plates and straddling his lap, a little bit of surprise on his face as she looked at him. 

“It didn’t hurt hardly at all. In fact, it felt really good.” She smiled softly, leaning in to kiss him. “Frisk. Careful. Even though I’m more in control than yesterday I still…” Frisk kissed him again, cutting him off. 

“I don’t care. I just want you today. I can handle my Master’s cock in me again.” She whispered, wanting to feel connected to him again like they were yesterday.

“Are you trying to seduce your master my pet?” He chuckled as she kissed down his chest, her fingers grazing against the front of his pants where she could already feel him hardening. 

“You did tell me not to leave my bed today. I just think we could liven things up a bit. Unless you don’t want me of course.” She breathed against his chest, looking up at him through her lashes.

“I always want you my pet. Always.” Gaster’s breathing picked up, grabbing Frisk hungrily kissing her as he flipped her under him, pulling his pants off quickly, his body so warm on top of her. Frisk moaned as he moved between her legs, using his tongue to prepare her for him.

He moved slow and deliberate, taking as much care with her now as he did when he’d broke her as his tongue curled up within her, stimulating her senses.

She was sore but it didn’t matter, she loved him, she wanted to feel him again inside of her, she needed him. When she was ready for him Gaster pulled her onto his lap, positioning himself under her. 

“I want you to ride me my precious. You set the pace today.” Gaster breathed as she nodded, easing herself onto him careful not to hurt herself until she was fully impaled on him. They moved slow, the pain mixing with the pleasure as she felt Gaster trying to keep from pounding into her.

“Master…please make me yours again.” She breathed as he growled low in his chest, grabbing her hips and thrusting up into her as she allowed him to take control again. Frisk cried out as she felt the strange knot starting to form again at his base, moving up his shaft slightly as he gripped her tightly.

“Frisk…my love…my good girl.” He groaned as he kissed her again, the knot forcing its way through her folds painfully. She gave a gasp of pleasure as they became tied to one another, their breathing heavy and their souls pounding in their chests. 

“I love you Frisk. I want you to say my name. Call me Gaster my love.” She tightened around him as she moaned, her climax rising within. “I love you…Gaster. I love you. I love you…” 

Gaster brought her mouth to his in a hungry kiss, her soul crying out silently for his as he thrust up into her, movement restricted by the knot. “Gaster!” She called out in a long drawn out moan as she came, Gaster quickly following suit, filling her up with stream after stream of his seed, the knot preventing any from escaping as he kissed her passionately, stroking her skin lovingly.

Frisk shuddered at the touch as his hips jerked into her in short bursts, each thrust shooting more of his cum into her. She tried to move off of him but he held her still, looking at her with an almost pained expression on his face that caused her to look at him in concern. 

“You can’t move yet. At least not until the tie goes down.” He explained and she looked at him in confusion at the term. “What does that mean? How come you’ve never done it before?” She asked as she ran her hands idly over his chest, her core hot and full. Gaster cleared his throat and tried to gather his thoughts.

“It’s a term used for breeding monsters. When a monster chooses a mate during their heat cycle there’s a possibility of being tied. It only happens if both parties are truly connected and their souls are compatible with one another.” 

Frisk frowned slightly as she tried to understand what he was talking about, his hands moving to rest lightly on her hips, thumbs rubbing her skin slowly as he looked up at her. “A monster can only impregnate his mate through this method and during the heat cycle. The knot keeps the sperm inside to get the best possibility of fertilization of the mate.” 

Frisk started to come to realize what he was saying. She looked at him with a bit of a blush. “It means that there’s a possibility of you becoming pregnant now. I should have asked first or told you but I got caught up in the moment. I wasn’t thinking straight.” Gaster seemed to look worried up at her as she blinked, feeling his knot starting to go down again.

“So could Sans and Papyrus do the same thing?” She asked with a slight frown, not liking the idea of anyone else being able to do this to her. “Only if you feel the same way as they do. Do you want them to?” 

Gaster asked quietly, his hands still on her hips as Frisk gave a soft smile. “No. I only want you do it to me. If I get pregnant, I only want you to be the one to make me so. I’m yours. Always.” She whispered as she kissed him again. Gaster smiled into the kiss as he wrapped his arms around her, pulling her close to his chest.

When the tie had gone down Gaster pulled out of her and lay them down on the bed together, Frisk laying partially on his chest and looking up at him while his fingers traced her spine, his other arm behind his head.

“Are you really ok with this? I want to be sure that you understand what this means for you and for me.” Gaster asked and she nodded slowly, a content smile on her peace. “I love you. I want you, only you.” She kissed the place above his soul, seeing it pulse in response through his ecto flesh. 

“Then that makes you my dam. The future mother of my pups. What do humans call something like what we have?” He asked, musing a little.

“Well humans don’t have heat cycles. But usually when two humans are together for a while and they love one another they get married. What about monsters?” She asked and Gaster smiled. 

“We pick a mate and for most monsters it’s for life. Skeletons are one of those that do mate for life. Then when the conditions are right we reproduce.” Frisk blushed a little at that and made Gaster chuckle at her expression.

“I think you would make beautiful pups.” He pulled her up towards him, Frisk feeling somewhat embarrassed. Gaster kissed her slowly, Frisk feeling happier than she’d ever been.

“But where would we put them? There’s no room here for children and neither is there room for them at your place.” She smiled and Gaster shrugged. “Actually, there’s a much larger area than what you saw at my place. I only made it smaller because it was just me. I can always make my lab smaller so that we can make room for the pups. It really wouldn’t be that hard to convert.” 

Frisk gave a soft giggle, Gaster rolling on top of her and pinning her under him, a soft grin on his face as he hovered above her.

“I want to feel you again. I want you full of my hot seed. I want you to be my dam to the pups I want to sire. I want to build a home with you. I love you my pet.” He breathed, rubbing against her. 

Frisk’s breath hitched as she felt him harden against her, his expression filling her up with love. “Tell me that you’ll be mine. Forever.” He whispered, brushing her lips with his mouth, his breath rushing over her skin. “Forever. I’ll be yours. I love you Gaster.”


	12. Chapter 12

They spent the rest of the day wrapped up in one another, the only time they were apart were when he had gone out to bring them food or when she had to go to the restroom. They didn’t see much of the others as they were so involved with one another that they couldn’t see the sideways glances Sans was sending their way. 

Gaster and Frisk eventually fell asleep in one another’s embrace, curled up under the soft blankets, content with themselves. Frisk was mostly asleep when she felt something long and hard slip between the lips of her pussy, moaning softly as it buried itself inside of her to the hilt, filling her up.

In her mostly sleep filled brain she heard a groan of pleasure as the hard shaft began to move inside of her. “Mmmm…so tight…” She heard Gaster growl in a sleepy tone as he thrust into her, Frisk beginning to wake as she moved against him, responding to his arousal instinctively. She heard the door open and close. the tingle of the excess magic filled the room announcing the arrival of the other two skeletons.

She felt the bed dip in two places as they came onto the bed, tongues running over their teeth and fangs, drool already dripping from their muscle. Gaster groaned in his sleep as he thrust into her, Frisk was silenced with a hungry kiss from Sans, his tongue ramming down her throat while she felt Papyrus moved to flip her onto her back without waking Gaster.

She obliged as Gaster remained inside of her, his body moving on instinct to keep thrusting up into her, laying atop one of her legs, the other hitched over his hip while the top half of her was on her back, pulled slightly away from him to give the other two better access.

Frisk moaned into the kiss as Papyrus mounted her chest, his large hands gripping her breasts and pushing them together, thumbs rubbing her hardened nipples while Sans pulled back from the kiss, kneeling in front of her as she let out a long moan, arching her back in the strange position as Gaster hit deep inside of her. “Fuck…look at that pretty mouth of hers…” Sans breathed as he stroked his cock, the tip brushing against her parted lips.

Papyrus groaned as his hips bucked against Frisk’s stomach, his knees keeping her arms pinned under him, his slick cock sliding between her breasts, still held together by Papyrus’s hands. 

She moaned loudly as Gaster slammed into her, still mostly asleep as he groaned. Sans guided her mouth to his hard cock, leaning over her slightly as he thrust into her mouth. Frisk moaned over his cock in her mouth, Papyrus thrusting between her tits, Gaster filling her pussy up with his large cock.

She came hard around Gaster as he pumped into her relentlessly, her moans vibrating around Sans’s cock thrusting into her mouth tilting her head back so he could thrust into her deeper, a long groan coming from him at the sensation. 

Papyrus bucked into the tight space between her breasts, her skin slick with pre cum as well as the strange lubricant that all three of them seemed to produce over their ecto genitals.

Gaster pulled back and hit deep inside of her hard as he came, the sensation causing him to wake fully as he sat up, blinking at the sight of Frisk being used by his younger brothers. 

He smirked as he pulled out of her, rubbing his eyes as he stretched, letting her turn her hips so she was fully on her back, Papyrus thrusting frantically as he tossed his head back, panting heavily.

Sans watched his cock thrust in and out of her mouth, tongue trailing over his teeth as several droplets of drool landed on her cheek. “Mmm…good girl…getting started early I see.” Gaster kissed the inside of her leg, fingers trailing over her skin before moving off of the bed, Frisk moaning at the loss of stimulation as Papyrus’s shaft hardened between her breasts, Sans growing close as well inside of her mouth.

Papyrus let out a grunt as he came over her chest, some of the pale orange landing up under the bottom of her jaw, his hips jerking slightly as he gave a shudder.

It wasn’t long before Frisk tasted him coming down her throat with a hiss, Papyrus getting off of her and licking her hardened nipples with a soft moan. Frisk swallowed Sans’s semen down her throat as he pulled out of her and kissed her while Papyrus fawned over her breasts, licking and sucking, his shaft rubbing against her stomach as he slowly moved his hips back and forth.

“Sans. Papyrus.” Gaster’s voice was deep and commanding, giving them pause as they stopped what they were doing and looked behind them, Gaster sitting in the love seat that had been moved to the end of the bed for optimal viewing pleasure.

“Which one of you is better at forming a pussy?” He asked, raising a brow as his cock stood at stiff attention between his spread legs. Papyrus and Sans shared a look of confusion before turning back to Gaster who was waiting patiently while Frisk sat up on her elbows. 

“I can do it pretty well but I’m not sure why you want to know this.” Papyrus offered and Gaster gave a pleased smirk. “Make one and lay in front of Frisk. She’ll take good care of you. Won’t you pet?” Frisk licked her lips, a little nervous since it would be her first time as she watched Papyrus moved into position.

Frisk crawled over to Papyrus as his magic shifted to form a vagina, looking over at Gaster for instruction before she proceeded. It was like he was a director for a porno as he turned to Sans who was eyeing Frisk’s backside and licking his teeth. 

“Sans you get behind her. Frisk, you take care of Papyrus like a good girl.” Gaster leaned back casually against the love seat as she nodded, Sans moving behind her and running his hands over her ass slowly.

Frisk turned her attention towards the youngest skeleton, his legs spread as he looked down at her with a faint orange flush. “Yes Master.” She whispered as she took a slow, deliberate lick, using the tip of her tongue to just barely slip between the folds. 

Papyrus’s breath hitched in his throat as she licked him again. “Hnnngh!” Papyrus shivered as she tasted him, glancing up at him through her lashes as Sans positioned himself at her entrance from behind. 

Frisk’s sense of smell was overwhelmed with the enticing aroma of Papyrus’s entrance as she moved her tongue through the folds, tasting him further, moaning against him as Sans impaled her on him.

“Ah! Frisk!” Papyrus gasped as she inserted two fingers, curling them up inside of him as she sucked on the bundle of nerves that was his clit, moaning as Sans moved from behind her, picking up the pace as he became more excited. 

Out of the corner of her eye she could see Gaster stroking himself, watching her with a pleased expression on his face. Papyrus keened as she ate him out, pumping her fingers in and out of him as he ground his hips against her mouth.

Sans cursed as he slammed into her from behind, fingers gripping her hips tightly as he tried to go as deep as possible. She ate out Papyrus, his hand going to the back of her head as he arched his back, his legs on either side of her trembling as she moaned against his pussy, causing him to cry out. Sans picked up his pace, thrusting into her as she started to tighten around him, feeling her climax bubbling to the surface.

“F-frisk! I-I-nyeahhhhh!” Papyrus cried out, forcing her head down as he came, his fluids running down her chin as she licked him clean, the sight making Sans lose it as well, coming inside of her just before she could find release and she gave a soft whimper escaping her lips as she looked up at Papyrus who was shaking with the stimulation, tongue lolling out of his mouth and breathing heavy as Sans pulled out of her with a long groan.

She’d been so involved with the younger skeletons that she hadn’t noticed that Gaster had come several times on her side, violet coloring her flushed skin.

“Come here pet.” He ordered, patting his thigh and she walked over to him, Gaster hooking his finger through her collar and bringing her face down to his for a kiss, turning her around and spreading her legs a little bit as he used his fingers to take some of Sans’s fluids, using it to lubricate her other entrance, Sans and Papyrus watching as they pleasured themselves on the bed.

She flinched a little bit as he shoved one of his fingers inside her tight ring. “Relax my pet. Remember what I taught you about this part.” She nodded and took a deep breath as he pumped his finger inside of her ass.

She gasped as he added a second finger, prepping her for penetration, Papyrus coming over to kneel in front of her, licking her entrance as Gaster stretched her out. She gasped as Papyrus inserted his fingers, rolling her clit against his teeth, the pain and pleasure mixing while Sans started stroking his shaft. 

“That’s it. You’re almost ready my pet. Thank Papyrus for making you feel good.” Gaster breathed behind her, adding a third finger inside of her as she moaned louder, looking down at Papyrus as he pumped into her faster.

“T-thank you Master Papyrus. Thank you for mmmm-ahhh! M-making me feel good! Nnnngh!” She moaned as she started to feel her climax starting to rise. Frisk was just about to come when Gaster pulled out his fingers, positioning her above his cock, the thick tip pressing against her hole.

She stiffened up at the sensation, feeling Gaster lean forward and kiss her shoulder, his breath shaky with desire. “Relax. I never hurt you before doing this right?” She shook her head and took a deep breath, Papyrus looking up at her between her legs as he continued pumping his fingers into her, curling them up and pressing up against her nerves from within.

Gaster lowered her slowly onto his shaft, the tip pressing through her tight ring, stretching her out as she let out a soft cry as he pressed further into her slowly until he was deep inside of her ass, Papyrus doing his best to distract her as she trembled on Gaster’s lap.

“Good girl. Easy now. You’re so tight for your Master.” Gaster growled at her ear, nipping at her skin and sending a chill down her spine. “If you’re good maybe the others will want to try.” Gaster moved his hips slightly under her and she let out a loud keen. “Shhhh…Quiet little one, we’ll take care of you. Papyrus.” 

Papyrus nodded as he moved to kneel, his magic formed his cock again and slammed it inside of her, making her feel full as she bit her lip trying not to cry out as a whimper escaped her lips. Sans got up and came to her side, grabbing her head and thrusting his hardened cock down her throat.

She moaned as all three started to move inside of her, the pain mixing with pleasure as the haze of pleasure ripped through her. Much like the last time Frisk was used by all three, their magic painting her skin, filling her up inside and leaking out from her holes with each new position. 

Sans came with a grunt as he thrust deep inside her ass, Gaster had finished inside of her and Papyrus had long since finished and was currently on the verge of sleep on the bed. “Fuck…so god damn good…” Sans mumbled as Gaster grabbed her, kissing her and pulling her into his embrace. 

“Let’s get you cleaned up my love.” He nuzzled her throat and drew her a bath. “You’re such a good girl. You feeling alright?” Gaster asked as he washed her down, paying special care to her more sensitive areas and running his long fingers through her hair.

Frisk nodded and yawned as she relaxed into the warm bathwater with a satisfied smirk on her face. “I’m always alright when I’m with you Master.” She glanced over at him as he knelt by the side of the tub, resting on his arms as he looked at her. 

“That’s my girl. But I think when it’s just the two of us you should call me Gaster. With the others you still refer to me as your master or sir.” She looked at him in confusion. “Considering you want to birth my pups I think at the very least you should be allowed to call me by my name. It could send the wrong message to the children.” He smiled and she leaned over, kissing him over the edge of the tub.

“When the heat subsides we will see if you’re carrying or not in the lab. But until then I’ll spend the night with you and the day prepping the home for our future. The boys will keep you company during the day and I want you to help them with their heat. Is that good with you?” Frisk nodded, pressing her forehead to his as the water helped soothe her muscles. 

Gaster smiled softly as he cupped her cheek, kissing her sweetly. “You only have to put up with it for another week and a half. It lasts longer when we don’t have someone to assist with our needs. After that you and me will be back home together.” He kissed the tip of her nose and she gave a soft giggle as he watched her.

“Do you think that Sans and Papyrus will need me after we have the children? Or they’ll be able to find their own humans.” She mused not really thinking about what she was saying as she looked up at the ceiling, not seeing Gaster’s slight wince.

“I don’t think that’s possible love. The barrier remember?” She nodded with a soft sigh as she recalled that they were still trapped Underground. “That’s right. The kids won’t know what stars look like will they? Or the warmth of the sunlight on their faces. That kind of sucks.” She sighed, smiling softly as she glanced over at Gaster who looked sad as he watched her carefully. “Do you miss the surface?” He asked quietly and she thought for a moment.

“I do a little. I miss the seasons and the fresh air mostly and being able to go anywhere I want. But I’m happy being with you.” She reached out and touched the side of his face, sensing his concern and smiling comfortingly at him.

“I don’t even remember what it felt like on the surface. Sans and Papyrus were still really young when I first brought them down here that I doubt they know what it was like.” He mused softly, kissing her palm. “Do you want to go to the surface?” He asked softly, Frisk thinking for a moment. 

“I’m ok here. I think eventually I’d like to go up to the surface again but for now I don’t mind staying here with you.” Gaster leaned over and kissed her deeply. “I love you.” He whispered against her lips with a soft smile.

“I love you too.” She smiled and allowed him to help her out of the tub, drying her off and taking her back to bed to find Sans and Papyrus sleeping soundly on the bed. Gaster and Frisk curled up in the space left over and fell asleep, the warmth of all three keeping Frisk warm comfortably.


End file.
